Are you allowed?

Me : I order a small beer, please
Waitress : That's all? Okay


*5 minutes later*
Waitress : I'm so sorry, but I really have to ask you a question
Me : Yes?
Waitress : Are you allowed to drink beer?
Me : What do you mean?
Waitress: Hmm, you know, are you over 18?
Me : Yes.
Waitress: I'm so sorry for the inconvenience
Me : Errr...