You bet your ass I feel like a fraud sometimes, Benedict Carey.
For example, I'm in an MBA/MA program for Arts Admin right now, which involves many classes in economics, finance, stats, and such. Cincinnati's MBA program is not exactly top-tier, and yet all these numbers and math classes are causing me trouble. To the point that I'm worried about failing the MBA classes and losing my scholarship. And this makes me feel like such an impostor: I have this paralyzing fear that although I've been "smart" my entire life (smart in the liberal arts way of reading and thinking and ideas), I'm just posing as someone who is truly capable of getting good/passing grades in a Real Degree Program and that I'm not able to do this on my own. It's extremely humiliating to constantly ask classmates for informal tutoring and help and clarification in the finance class, especially since I've never, ever had to ask for academic help from anyone. And since it's becoming clear that all the good-at-math kids are really sick of saving my ass on every test, I feel like I'm verging on having to find out exactly how little capability I actually have.
Of course, I still have to present myself as Ms. Take-Charge-and-Kick-Ass, which feels like it'll set of a big flashing neon sign of "FRAUD ALERT!" over my head.
So YES, Mr. Carey, I feel like an impostor. Thanks for reminding me.