Your credit card does get you Zone 2 boarding, but I seriously doubt that did you any good at all when you were late for boarding your connection. We faced a similar situation in San Francisco last year, when we arrived at the gate just as they had closed the doors. We were flying First Class, and are also AAdvantage credit card holders, and we were not permitted to board. I'm sure our seats had already been given to others. You just got lucky.