Navbar tabs collapse from right to left as the screen width decreases. If you go narrow enough the only tabs left are Home and Forums. That behavior is as expected. However, the sublinks for navbar tabs collapse in the opposite direction: from left to right. I expect sublinks on the left to be of equal or greater importance to the sublinks on the right, so this behavior is not as expected.
Is there an easy way to make sublinks collapse from right to left?
It is as expected. If you look at the subnavigation for the Forums tab, the most important link is New Posts followed by Watched Threads. It's similar on the media tab with New Media and Watched Media. Users want to access new and watched content before anything else.