I've never had a problem either, actually, but I did a fair amount of flying in the first few years after 9/11 and got *really* paranoid about what I'd carry because the early TSA was so very jumpy and inconsistent. At this point it's mostly habit - though in fairness, I'm pretty sure the round cutters actually are a large enough blade to be banned.

(Nail clippers in the very early post-9/11 era could be an issue if they had the nail file that pivots out. I think the theory was the file could be sharpened into a blade? I wish I was kidding.)