It could be an honest compliment. Enjoy it.
A compliment is a way to get close enough to you to confirm their suspicion that they clocked you. Many of us are passable at a distance but not so well close up. Where I live, undercover cops often use compliments to get close to a suspect and to get a reaction that they can use as a field sobriety test, so I am more cynical than most people about things like this.
