The mysterious world of Op-up

So I got op-uped on my flight to Washington DC from Heathrow. These are the best upgrades you can have. Because it costs you nothing. I board my flight as usual, found my seat in Economy. I got settled in, waiting for the rest of my flight to board. 10 minutes later I saw the gate agent come on board. She stopped by my seat, handed me a new boarding pass and said "Here is your new seat Mr. Lee. Happy holidays!"

What the hell is an op-up? An op-up is a shorthand for operational upgrade. The airline upgraded you based on their operation need. The easiest example is that Economy is oversold and there are empty seats in Business. Instead of bumping people, they decide to upgrade certain passengers based on various factors, usually booking class of the ticket or elite status.

Here is the thing: Airlines have gotten really good at managing their load factors. Operational upgrades don't happen much anymore. On top of that, on this flight I was only United Silver, the lowest tier in MileagePlus. If I was upgraded because of status, that would mean there were no other Gold / Platinum / 1K / GS, which I find unlikely. I also talked to the gate agent before boarding, and while I was nice enough, I didn't have enough of a conversation with her to make a lasting impression.

This was only the 2nd time I've been op-uped. Who know why it happened. Not going to complain!`