Settings API: Two update notices after saving settings?

I’ve used the settings API to create a very simple page for plugin settings. This is my first time using the API, and through various tutorials online and answers here, I think I’ve figured it out. This is backed up by the fact that the page even works!!

However, something weird is happening:

As you can see above, there are two div.update messages being displayed on the screen. I’ve checked and there’s only one call to the settings_errors() function so and that function isn’t called in a loop or anything that I can find, but I’m still getting two notices.

Here’s the code:

public function __construct() {
    /* more stuff */

    add_action("admin_menu", array($this, "plugin_settings_menu_add");
    if($pagenow == "options.php" || $pagenow == "options-general.php") {
        add_action("admin_init", array($this, "plugin_settings_initialize");
    }
}

public function plugin_settings_menu_add() {
    add_options_page("Gallery Settings", "Galleries", "manage_options", "galleries-settings-page", array($this, "plugin_settings_menu_display"));
}

public function plugin_settings_menu_display() {
    require(plugin_dir_path(__FILE__) . "views/plugin-settings.php");
}

public function plugin_settings_permissions_to_use_default() {
    return apply_filters(
        "plugin_settings_permissions_to_use_default",
        array(
            "galleries-settings-permission-to-use-url" => ""
        )
    );
}

public function plugin_settings_initialize() {
    if(get_option("galleries-settings-permission-to-use") == false) {
        add_option("galleries-settings-permission-to-use", $this->plugin_settings_permissions_to_use_default());
    }

    add_settings_section(
        "galleries-settings-permission-to-use-section",                    // DOM ID for the section
        "Permission to Use Gallery Items",                                        // on-screen title for it
        array($this, "plugin_settings_permissions_to_use_header_display"),        // callback to display its header
        "galleries-settings-page"                                            // the menu page on which to show it
    );

    add_settings_field(
        "galleries-settings-permission-to-use-url",
        '<label for="galleries-settings-permission-to-use-url">Webtools Form (required)</label>',
        array($this, "plugin_settings_permissions_to_use_url_display"),
        "galleries-settings-page",
        "galleries-settings-permission-to-use-section"
    );

    register_setting(
        "galleries-settings-page",
        "galleries-settings-permission-to-use",
        array($this, "plugin_settings_permissions_to_use_sanitize")
    );
}

public function plugin_settings_permissions_to_use_header_display() {
    echo "<p>......</p>";
}

public function plugin_settings_permissions_to_use_url_display() {
    $settings = get_option("galleries-settings-permission-to-use");
    $value = isset($settings["galleries-settings-permission-to-use-url"])
        ? $settings["galleries-settings-permission-to-use-url"]
        : ""; ?>

    <input type="url" id="galleries-settings-permission-to-use-url"
        name="galleries-settings-permission-to-use[galleries-settings-permission-to-use-url]"
        value="<?=esc_url($value)?>" class="regular-text" required aria-required="true"><br>

    <em>Enter the full URL but without any query string parameters.</em>    
<? }

public function plugin_settings_permissions_to_use_sanitize($input) {
    $output = array();
    foreach($input as $key => $value) {
        // even though we have only one field here at the moment, we'll use a loop and a switch
        // to santize.  that way we're ready to go with respect to additional data that might one
        // day be sent here.  

        switch($key) {
        case "galleries-settings-permission-to-use-url":
            if(empty($value) || !filter_var($value, FILTER_VALIDATE_URL)) {
                add_setting_error("galleries-settings-permission-to-use-url",
                    "galleries-settings-permission-to-use-url-invalid",
                    "You must enter a valid web address."
                );
            } elseif(($qloc = strpos($value, "?"))!==false) $value = substr($value, 0, $qloc);
            break;
        }

        $output[$key] = $value;
    }

    return apply_filters("galleries_plugin_settings_permissions_to_use_sanitize", $output, $input);
}

The following is the contents of the plugin-settings.php page that’s included in the code above:

<div class="wrap">
    <div id="icon-options-general" class="icon32"></div>
    <h2>Gallery Settings</h2>

    <? settings_errors(); ?>

    <form method="post" action="options.php">
            <? settings_fields("galleries-settings-page"); ?>
            <? do_settings_sections("galleries-settings-page"); ?>
            <? submit_button(); ?>
    </form>
</div>

And, yes, as you can probably tell, this is Yet Another Image Gallery Plugin. I did do a search and replace to hide some of the information about for whom I’m doing the plugin. Hopefully doing so didn’t introduce any errors.