I've noticed that some people really hate being called by their surname.
It doesn't bother me. If a friend or acquaintance comes up and says hello "surname," then I don't care. But I know some people who really hate it. They take it as a mark of utter disrespect and it makes them really angry. I've had colleagues at work try and have me disciplined over it, even though they are no higher on the totem pole than I am.
Does it bother you, or anyone you know?