WordPress tries to load “next page” after done loading current page

I have a fresh 3.5.1 installation – default theme, no plugins.

Running HTTPFox on Firefox shows that after a GET-request of any given page in WordPress has finished loading, a GET-request is sent for the rel='next' page:

<link rel='next' title='Next Page Title' href='http://www.domain.com/next-page/' />

and fails:

00:10:04.992    0.556   698 245 GET (Aborted)   text/html (NS_BINDING_ABORTED)  http://www.domain.com/next-page/

My question – is this on purpose? Is wordpress doing some kind of preloading? I’d like to understand why it is doing this.