Pick up line

Went to a nearby grocery to get some emergency milk and Nutella just now. Checked out at this counter, which I am quite sure the cashier is new, and he looks like a high school kid/college freshman. Anyway, I had the following conversation with the young chap...

Cashier, "Do you have a xxx (the supermarket name)..." (asking for the supermarket reward card)
Me,"No." (used to shop there too often until I know what the cashier would normally ask.)
I saw the amount on the display, and was digging into the wallet... then I heard the cashier asked, "Do you have a phone number?"
I thought he was repeating the reward card question, and I blurt "No" instantly, without listening properly what he actually said... then I raised my head from digging into the wallet, and asked, "Pardon?"

He repeated, "Do you have a phone number?"
OK, this time I heard properly, smiled and replied, "No."

He gave me the change, and greeted "Have a nice day."
"You too." and I left.

I thought no one would be interested in a messy, plain, almost ugly girl like me. Whether or not he was just asking for fun, I sure am flattered now. :)