What not to say/do. Installment #1

I notice a lot of situations where I think "That probably was not the best thing to say or do." I am no etiquette expert, but I like to think I could teach these folks a thing or two. In this light, I bring to you an ongoing segment called "What not to say/do"
In today's lesson Carrie is buying a bottle of wine at Publix. The cashier is in high school (I know this by the conversation he was having with the boy bagging my groceries). The cashier cards Carrie, who is 31. She is flattered momentarily:

Dear High-School boy that was my cashier at Publix -

At first I thought you carded me to buy the bottle of wine out of obligation. You know since a lot you wear that we card EVERYONE button. I quickly realized that you, in fact, thought I was underage. I was flattered, at first. I would like to say that in the future when you card a 31 year old, look at her ID and realize she is 31, the best response is probably NOT
"WHOA - I didn't think you were that old. You don't look THAT old!"
There are a lot of acceptable, flattering responses to make the same point (some even still use WHOA).

Here are four:
1 WHOA - I would have never guessed you were 31!

2 Well excuse me. You don't look old enough to drive without a licensed driver in the car, yet you have been of age to buy wine for 10 years now.

3 Hmmm....31 eh. I can only hope I age as gracefully as you.

4 The simple, yet highly acceptable...Thank you maam!

Sincerely-
The 31 year old you carded.