You didn't actually make contact, so I wouldn't view this as a rejection, because he had nothing to reject. If you were waiting for him to make contact, his not doing so is not a rejection--he merely did not do what you hoped. Right now you're just a guy he may have noticed watching him, and that might even make him a little uncomfortable. Have confidence in yourself & try talking to him. Maybe it will lead somewhere (possibly just a short exchange, possibly more), or maybe not, but it's worth a try.