To clarify a couple of questions, I was confirmed at the AC, issued a boarding pass for the earlier flight, and placed on the upgrade list, where I was first with one unsold seat. I did not pay a change fee, so in that regard I was receiving a courtesy.

I was unaware that the crew member took seat 3A until I boarded and saw him sitting there. All I knew for sure was that the individual in question was called up with the standby's, and at that point they announced that first class had checked in full. There were not a lot of standby's and coach was less than 75% full. Most of the middle seats and even a few whole rows were empty

Either way, in that particular situation, I was not particularly vexed by it. I was given great treatment at the AC and given an aisle with an empty middle next to it. If first was important to me I would have waited until my original flight. I don't drink on flights and for a short hop, a coach aisle with an empty seat next to and in front of me was almost as good to me as a bulkhead window in first. I just shrugged it off and only mentioned it because I was reading this existing thread. Besides, if I did complain I think it's just as likely that the AAngel who processed my boarding pass without collecting would get in trouble as the gate agent.