Ah yes.. I've got a mod installed and that doesn't show for me.
Anyway, it's done in includes/class_groupmessage.php in the function filter_sort_field. It looks like there is a hook to affect that area called album_sort_field. So, you can play with that if you want to change what it is sorted on. The DESC and ASC are options that are passed, I think in album.php around line 1789:
PHP Code:
$collection = $collection_factory->create('album', false, $vbulletin->GPC['pagenumber'], $perpage);
You could pass a fifth paramenter, the default is DESC (which is why they didn't pass it since that is what they want).