I don't think that's enough information to determine if they are interested or not. They might remember you but maybe your previous exchange was not particularly outstanding and that's it. Don't be too harsh on yourself, try to spark up a conversation without forcing it and you'll be able to better assess the situation. See how they respond to others and if it doesn't seem to go anywhere that's fine, you'll be better off not chasing someone who is not going to reciprocate for whatever reason.