I have had some very odd questions from immigration officials, but the key is to be honest and stick to that story, half of the questioning seems to be checking for self-consistency.

I've previously been hassled for not knowing the dates of my last visit (at the time, I was travelling abroad weekly - sorry, but as nice a place as the US is, it's not important enough for me to memorise dates), and, the most bizarre of all, for "spending so much time out of the office I can't possibly get any work done".