[A tic? He never thought of it in that way, but he... supposes it is.]

When I feel... anxious before something important, or if I just want to gather all my focus into a single point, I use my coin.

[Here, he digs in his pocket with a free hand. Yes, he took it with him when he changed clothes, and he only needs one hand to demonstrate.

The quarter shines silver in the light. He flips it with a high, metallic ping and catches it against his knuckles, rolling it across the top of his fingers.]

I don't know why it works, exactly, but it does. It was never something I was programmed to do.