I think I may be able to enlighten you as to what happened. It sounds like the first officer you saw, for whatever reason, doubted your identity. That would explain the referral for further examination. It would also explain why the officer would be asking you odd questions. Think about someone trying to sneak into the US on a fraudulent document. That person would likely have prepared answers to such common questions as work, home address, etc. I have to admit the firearm question confused me slightly, though.