Let's get back to helping >>1, shall we? We don't want this thread turning into something it's not supposed to be.

It probably bothers you a lot because she's not being completely honest with herself around you. Like >>9 says, for some reason a lot of guys just stop liking a girl just because she seems smarter than they are. She probably thinks you're doing the same thing, and the fact that it bothers you might add to her insecurity. If you're more than sure that she is truly pretending, then I think you should just confront her about it, and maybe tell her than you're okay with her just being her normal, incredibly intelligent self.