So far, so good. He was jazzed right after, not upset but kept asking me to explain how it happened. Then he was tic'ing a lot more than usual for the next few hours, but settled down again by dinner. He missed cello because of it, so he probably considered it a blessing.
I expect it will stay forgotten until we have to explain what happened when we go to cello next week--that's when it will turn into a thing, if ever.