I need advice

A couple weeks ago I went to this coffee shop that I never went to before. The guy that worked there happened to be an old friend from a mental hospital I used to go to. I ordered a hot chocolate and when I went to pay he said "your total is $0" with a smile on his face. I was in complete shock and of course argued with him but he said it was on him. Was he just being nice or do you think it was something else? I've never had something like that happen to me before...