This odd encounter happened when I was flying AA
a few years ago. I believe the plane was a 757 but I may be wrong. I was sitting in the waiting area and saw the plane I would fly. A member of the crew opened the door on starboard and then closed it. He opened and closed it five more times. It opened again and this time, someone on the tarmac was looking up at the door. After the seventh try, they left. Were they checking the door seals? Or is the cabin pressure kept slightly high so that it exerts force on the door to keep it shut in case the locks should fail? I don't think I saw any safety crew board the plane. They just loaded it up and left. Yes, I got on the plane too and that strange sight has always made me wonder. Can a flight be grounded if any member of the crew SUSPECTS that any door on the plane could be having problems?