You protest that she didn't mention anything in the phone call at early morning, and that when she said meeting now, she didn't mention it is in her office, and that you went to the meeting room and waited her there as meetings always done there.
Then a smile is drawn up on her face and she say: " The meeting room is when we are making the meeting for the whole department, not for a small meeting between me and you."
You smile back for her and then you notice,