This is the "three hour mark" upgrade. We likely need to come up with a better term. EUA, now, processes upgrades 3 hours before departure time and sends out an email. If you have the email sent to a pager or text cell phone you get the notice about 3 hours in advance - you might be driving to the airport. I also have had this happen on a second segment, while waiting at the gate for my first segment. Having received the email (on the cell phone) I just went to the counter and got the new boarding pass. I told the gate agent - I just got the upgrade message for my next segment - could he please give me a new boarding pass.

I am also finding that you never get upgraded when you check in. If you do not get upgraded via EUA during the overnight processing (1-5 days out) - then you will always be on the standby list when you check in, or get EUA processed at the 3 hour mark.