When NOT to Bring Out the Calculator

So, I've never been a waitress. I've worked at ice cream shops and coffee shops before, though, so I know a little about how to treat customers. One thing I would NEVER do if I were a waitress would be to bring a calculator over to a table who I thought had tipped me too low.

Somehow, though, my waiter at Locke-Ober last night thought this was perfectly acceptable behavior. True, we tipped on the Restaurant Week price and not typical menu prices (although we never even saw a regular menu, so I had nothing to base that on), but a calculator? And he kept saying "I'm sure you meant to tip me well, but..." like we were a bunch of children in school who had done our math homework wrong.

Thanks, but I deal with enough pretentiousness without it being fed to me with my dessert.