Just out of curiosity, I'm wondering how on earth I was upgraded on a flight from ORD-SFO during Thanksgiving weekend (Sunday). I'm a lowly 2P, upgraded only once before since obtaining status, but I cleared at the 24-hour check-in window, with First showing 4 empty seats (out of 24) at the time.

This was a completely full mid-day flight with 182 people on board, on a route that's typically very elite-heavy. I'm normally something like #40 on the upgrade waitlist, and I don't think my fare bucket was significantly higher this time around.

What happened? This has me wondering if there might be an unwritten policy of automatically upgrading Premier members after a certain number of failed upgrades. Is it possible?