The compliment every girl waits to hear

At the grocery store the clerk asked me to show i.d. for my adult beverage purchase. The following is our charming exchange:

Store Clerk: May I see your license?
Me: Sure
SC: (upon inspecting said identification) Wow, you must be doing something right!
Me: Well, thank you (in that ducking-the-head kind of bashfulness)
SC: (after looking at license again) You don't look THAT old!

Really? THAT old? How old is that? I am 28. He acts like I just got out of my crypt and dragged myself over to the f*cking Winn-Dixie for a draught of ale. Damn. What a terrible way to end a compliment.