I had a very similar problem to the original poster in SFO, except the argument was that I had three bags (laptop, overnight bag, flight kit). Supervisor had to explain that I was exempt because I was crew. When I got to the gate the gate agent wouldn't let me on and told me that I was in violation of my passrider TOS. When I told him I was crew he said it didn't matter because I was not in uniform. Had to check my bags, and wait four hours for a flight I barely got on.