Originally Posted by
diburning
Many factors:
3. They could have SDC'ed or changed onto the flight after you cleared.
Or they simply booked flight relatively close-in after the last C+ upgrade. Anybody booking a day or two out is going to have a relatively high fare class (due to advance purchase requirements on cheaper fares) and they will have a higher upgrade priority compared to someone with same status level on an advance purchase fare in a lower fare class.