You had a nice chat with the fellow because he was robbing you. First flag should have been thst the auction was not over - 2nd flag was that you were communicating with them outside of forum (I assume this because until recently you had limitations) all you needed to do was to share the txn id. I would ask - what did you receive and from whom did you receive a message with a different address? Or a link to communicate outside the forums?

There are scammers constantly watching these threads to prey upon buyers and sellers alike.