It is actually pretty common from what I have seen. Especially when someone else is the person actually getting work out of the student and the advisor is mostly responsible for pay+graduation.
He's (presumption?) probably tired of you calling him a tard.
That can be confusing, because I swear I think that sometimes KH calls someone a "tard" out of affection and at other times he really is calling someone that because he hates that person more than the swine flu.