Looking Silly Is Good.

He has a lot of questions that he has wanted to ask her ever since he saw her message. But this question is the most important one that he can get an answer to. 

"I don't like where this is going."

He continued with his inquiry despite her reluctance. "How long have you been pretending not to know about my divine ability?"

Her reply was laughter. She covered her mouth and laughed. He nodded to himself. Her reaction is answer enough for him. She is laughing because she found something funny. It is probably his ignorance that is making her laugh. 

He should have known that his divine ability is not secret anymore when she brought 6 sheets of paper at that meeting to invite him. She obviously prepared for his ability to see the past in mana. She just prepared badly so it looks like she didn't know.