I purchased W bucket RTs IAD-SFO-IAD and upgraded the return leg with 15K miles.

The return leg (flight 872) appears to be on a 3 class 763. I was offerd C seats and chose 8E and F. Checking .bomb my seat assignments have been changed to 1A and B.

Can I expect to keep these seats for a December flight or should I call and switch back to C seats before UA does it for me?

Thanks.