You were on UA1066?

My first thought was:

1. Redacted passenger was on previous flight
2. Passenger did not board, skipped eating, or went with another option
3. Meal lingered in galley to be used on next flight
4. Catering at your origin station didn't have any cheese, so your cheese pre-order was essentially cancelled
5. FA had list showing you had no active pre-order (bcs it had been cancelled)
6. Before going through cabin, FA did an inventory of what was in galley and noted cheese plate was available (even if not on their catering list)
7. FA approached your seat and offered the various options, including cheese plate

But if the sticker had your flight number on it then I guess not.