This an operational upgrade. It happens when there are paxs trying to get on a sold out flight where Y is full but F (or J for a three class) has open seats. The GA will then UPG an elite flier form Y and place a standby in his/her original Y seat. I have gotten many of these as GOLD and PLT (I tend to fly when there are a lot of leisure travelers on routes like JFK/MIA and JFK/SJU). If you are UPG you should not be charged stickers (unless the GA advises you so and you constent). Call the PLT line (really not a PLT per desk per se, call just gets routed quicker) and politely ask that stickers be restored.