Apologize for a misunderstanding

Security guard: G
Dean: D

G - Excuse me. Can I have a work with you?
D - Yes. Is there any problem?
G - I'm afraid so. Did you know that this pub isn't aloud for people under 18s?
D - No, I didn't.
G - Didn't you see the sign?
D - No, I'm afraid not.
G - Have you been here before to drink something?
D - No, that's the first time I come.
G - Well, if I were you, I'd look for a different place.
D - OK. Sorry about that. I didn't realize.
G - That's OK. Remember for the next time.