Would you have been offended?

I've been a waitress for 10+ years and I've worked in a few sports bars and let me tell you, that guy that said something about your son is the SAME guy that complains about his food, complains about his service, wants to talk to the manager and doesn't tip. Some people are just grouchy, bitter a**holes. I wouldn't let it bother you. You're a good Mom, you know that.