So by now, I'm sure a lot of people have seen it: A Hunter accompanied by what looks to be a pet on steroids, with a huge size and an elite target frame. No, Hunters have not gained the ability to become even more imba, it appears to be a display bug. Since 2.4, elite and rare (aka silver elite) pets aren't quite registering properly once tamed, as they appear to keep their size and show up as elite in status (though apparently not in stats) until the hunter logs off. As a result, you may have seen Gutripper tearing up Blood Elves in Dawnblade Village, or King Bangalash frolicking around Booty Bay. Rest assured (or be disappointed) that you probably won't see them that way for long, and a hotfix is on the way.
Mania speculates that the bug may have something to do with the implementation of Papa Hummel's Pet Biscuits, which seems very possible. Maybe when they messed with the coding to allow pets to grow larger, much like the PTR bug where non-combat pets grew giant, it caused elite pets to grow a bit larger too, or at least not shrink like they should. Either way, enjoy your new massive pets while you can, Hunters, I'd imagine a hotfix will come either this Tuesday or the next.