Leonard stumbles back before he can catch himself, just a step or two, but still. Definitely affected. He doesn't point it out, he waits for Mick to let it register, if it even would at all. "I wasn't going to let you do it, was I?" As if Mick wouldn't have stopped him. But that's beside the point, because Leonard has planned for it. Of course he has.

"Something like this was the only thing that could have kept me from coming back for you before." All interconnected. All leading up to the same conclusion.