This reminds me of a flight from LGA I took this summer, the most bizarre handling of a potential oversell I've seen. Maybe this is AA's new strategy?
They did everything they could to increase the chance someone would inadvertently miss their flight. I have mixed feelings...I don't pity people who forget their departure time, but it left me with an icky feeling from AA.

Here is how it went down.
I received multiple text messages that my bid was being "considered" and to go to the gate. I usually aim to be the last person to board so I saw the entire mess of a process .

GA: Passenger [me] please check-in at the gate (about T-20).
Manager: Dont page anyone! No announcements!
GA: But this was a volunteer.
Manager: Doesn't matter! No paging!

There was NO GA "final boarding" message. Maybe an automated airport one, I am not sure.

FWIW - no volunteer was needed and I think they even cleared standbys. The most customer unfriendly approach I've seen but I guess at least it's a strategy? Maybe the same thing happened to your flight except AA wasn't as lucky.