Encounter at the Check Out

I stopped at the local market to pick up some bits and bobs on my way home from work yesterday. I was already thinking of my next errand when the cashier asked me if I had a reward card.

But, of course I have a reward card!

I handed it over, she scanned it and completed my transaction. Handing my receipt and change back, she glanced at the bottom of the receipt and said:

Thank you, and have a great day Mrs...um...Valued Customer!

What's a polite shopper to do? I replied:

Thanks and good evening to you, Miss Tom Thumb Cashier!