I guess. For some 3 of a suit on 5th is a flush draw. But in general, If you have a high pair on board, and more so if its the door card, and someone else raises into it on 5th or higher, you are usually in big, big trouble. Some people won't fold there becasue they feel that someone is trying to put a move on them by raising their on board pair. If a player plays like that,as your opponent did, he will usually wind up all in sooner or later. It was a nice win for you.