Cass smiled. 'Oh I'm not angry, don't worry about it.' Maybe a bit disappointed that they didn't trust him more, but he'd never let them see it. It wasn't as if he trusted either of them with everything after all, so maybe he did deserve that?
He could see a diversion as much as anything though, and he wasn't an Auror for nothing. He knew when to back off. Well not often, but sometimes. And Harry was looking more uncomfortable by the minute.
Instead he chose to focus on her last statement, smiling. 'Not so much uncomfortable as terrified,' he joked with a wink. 'I'd be a menace to her I'm sure. I wouldn't want to subject her to me.'