A snippet of my day

I am cutting up stuff in the copy room in a vague attempt to look like I do have a job to do when a new teachers, Mr S comes in.

Conversation is as follows (in Japanese):
S: sorry (as squeezes past me to get to the photocopier)
N: soooo, you're new here, aren't you? How is it? (Hope that sounds less flirty in Japanese)
S: oh, you know, only been a few days, but seems like a nice school.
N: yehr...where were you before? (inspiration! This conversation will last more than 3 lines)
S: I taught at (insert long name of school I have never heard of)
N: I see. Did you have an ALT?
S: Yup, her name was (insert name of ALT I have never heard of - which could be anyone on JET as I only know J and H)
N: Oh. Don`t know her.

I turn back to cutting up pieces of paper and he starts copying.

Several minutes later, from the vicinity of the back of a rather angry copy machine
S: (in ENGLISH) Oh, S*%T!!!

Why? Is this a mistake on my part and he really said something else? Is it a secret code to tell me he can speak English without actually having to say so to my face? Is it just that he is a rather strange man? Only time will tell.