She sounds cranky and used poor communication skills. A lot of people disregard boarding order and the airline should make sure those who paid the money to sit up front are afforded the benefits of their ticket like getting on quickly and comfortably. This could be done in a way much more professionally than what happened to you. Shoot AA a message if it's still ticking you off, I've found them pretty receptive if you're being reasonable.

Extra comment: I am a scruffy 20-something who changes into very casual street clothes before I fly (comfort and it prevents other consultants from talking to me about "what I do" when I finish a long week and want to be a human again). I am almost always in first and probably fly more than all the three-piece suit folks in line with me combined. I am cut in line ALL of the time by people who assume I'm sitting in the back. Everyone makes assumptions at the airport.