I thought I had problems when travelling to San Francisco's Web 2.0 Expo this year but I never thought customs officers would make you as US Citizen problems. Crazy!
US citizens may have more to worry about, actually, since the most they're likely to do to a non-citizen is refuse entry, but a citizen could easily wind up in jail for years for, in the recollection of the officer, lying to a federal officer. That was all Martha Stewart was convicted of, after all.