You're on an a/c without a boarding pass.!!!
You are required to keep your boarding pass with you until you reach you final destination. In this day and age, I would not be surprised that a F/A would act this way, infact I would expect it.
If you thought you were being treated like criminals, try taking an El Al flight to Tel Aviv. They hand cuff you to the seat if you even look at them funny... Hi to Andrea if you see this!
I was on an flight and prior to take off, I went to the bathroom because I wasn't feeling well. The crew were frantic about my small bag that I had left under my seat, and were about to remove it from the aircraft.
Just be thankfull that the crew on your flight were being security concious!!!