Do you think this bloke fancies me?

A bloke I know works down the other end of the corridor in I.T. He's quite 'a lad' - likes to drink a lot. We have really hit it off and often meet on the way into work and chat. Ever since I've started talking to him, he now says he's not doing much at the weekend and now just going to relax. It seems a sudden transformation to how he normally lives. He's quite nice to talk to, but suddenly he seems to want to clean up his act and I wonder why he's behaving this way?