I confirmed that I was a US citizen when I was stopped in CA — twice in the same week. I refused to answer any other questions as to destination, length of stay, etc; the more so because I was just road-tripping the time I was questioned, and really didn’t know those answers precisely.
I have to say that my weirdest encounter with USBP came on the Canadian border, re-entering VT from Quebec. I mentioned that I was visiting a friend, and the little dickweed Napoleon (French name, too) kept grilling me whether she was my girlfriend. Last I checked, unless I was smuggling her into the country in my trunk or had drug-resistant syph, it’s not illegal for me to boink a Canadian.
