Mikami stumbled backwards when he was released, his necessary bubble of personal space rather suddenly expanding quite a bit. It wasn't that he was shy - you couldn't be an excellent lawyer and be that shy - but simply that he was not interested in anything that Grell seemed to be ... hinting at. Yes.
He recovered fairly quickly from that unpleasant little shock, though; he had after all had far worse surprises, and recently, too. "Do you use Death Notes, or know a shinigami called Ryuk?"