Yeah it sucks the guy didn't tip you, but what reaction would you expect from bringing it up? Ydi

When he went through the trouble of paying in exact change, he wasn't forgetting the tip -- he signaled he wasn't going to tip. It was out of line for you to ask. This is why I hate tipping! Service people should be paid fairly without having to rely on some social dance.

Few years back, I delivered pizze as a short-term contract job. Whenever people tipped me, I would accept it and say "Thank you very much, enjoy your pizza". To no-tipping customers, I would say "Enjoy your pizza". Do not expect all your customers to give you a tip because they don't have to and most of them will not. Be grateful to tippers and always remain polite, no matter what. Anyway, that customer was a total ass but since there are many good reasons why people don't tip, just don't ask !