Earlier this year (Feb in FLL, IIRC), this even worked (properly) when I did the $25 same day flight change. Even though I changed to a new flight at the Kiosk that was leaving in UNDER an hour (and, FWIW, my original itinerary was platinum and companion upgraded) -- the gate agent "re-did" her upgrades and had us upgraded by the time I got to the gate.

The only reason why I know this.. Because when I got to the gate, she was calling my name; and then said "I had already completed all of my upgrades and then I noticed 2 platinums pop up -- so, I re-did my upgrades and processed you."

That was one incredible GA, WOW !