I have been in a similar situation, where one interview's curveball ended up being asked in a subsequent interview. I went through the same emotions as the auth

I have been in a similar situation, where one interview's curveball ended up being asked in a subsequent interview. I went through the same emotions as the author (including resisting the urge to grin from ear to ear). But like an idiot, I answered with the trick answer right away (though I was calm about it). I then told the interviewer that I had learnt it in a previous interview. It turned out he was looking for the clever answer too; and he was disappointed that I knew it. Maybe he felt I wasn't sufficiently "excited" about the clever answer, but I never got the job. Which is not too bad, since that outfit wasn't my first choice anyways.