I experienced two (2) types of new upgrades this weekend:

First was about 1 hour, 10 minutes out (before the gate even opened). I had checked upon arrival in IAH and was not upgraded. Later in the PC, I looked at my itinerary, and I was upgraded. I exchanged BPs at the PC. Then later, a redcoat came on the plane to verify I had gotten my BP and was in F.

The same thing happened in EWR. I was rebooked onto a different flight and added to the F standby list about 90 mins prior to departure. A little over an hour beforehand, I refresh my itin, and there it is. Exchange BPs and I'm on my way.

So that's not an EUA, nor is it at the gate (the gates don't open until 1 hour prior). So I think a redcoat or someone is watching the flights and processing gate upgrades a bit early if it's possible.

Second, after enjoying a pre-departure beverage, I was pulled off a flight with a mechanical (along with 2 other plats) from our F seats and rebooked because it was believed we would misconnect. After we got rebooked, I reminded the redcoat to please upgrade three (3) more Elites, as we had just offloaded 3 F seats. From his reaction it sounded like he didn't realize we were in F, and he went over to process them. So it's possible to get upgraded, even after F is fully boarded!