Sold an item but you haven't gotten your coins yet? Read here

Basically the clock continues because other people are still on the player's screen. They can still look at him for about up to 15 seconds until they have to either buy him or exit. If they buy him than you basically lose the player even though it says you won him at first. Try cheking your bids the moment after it says "you won" because unless it says "this is your winning bid" high chance someone else is either bidding or buying him.
P.S. If he does not buy you might get him if you are fast enough!
Hope this helps