Had this happen to me over the weekend as well. Bought stickers Friday night for Sat 1 PM flight. Hadn't posted and had to buy the needed ones from the agent (I know I could have gone to the kiosk, but at that point it wasn't worth saving $10). Had I known they hadn't posted, would have checked in at the kiosk. I didn't get the receipt until Monday night, 3 days to post. At least they were in the account for the return trip