I once had a very similar experience at GWB in Houston, except it wasnt even 4am. I was just highly confused when the lady started yelling at me to take off my belt.

As I was complying, apparently the right thing to say was not “Im sorry, they didnt make me take my belt off at XYZ airport earlier”, because Im fairly certain that response almost earned me a trip to the special area and an all-expenses-paid cavity check. To say she was unpleased would be a massive understatement