Honestly, yes. When I saw the title of this thread I thought the OP was going to tell where Goofy purposely decked someone, because they odds are so low that it would ever happen. The low odds are what would make it a story. While shocking without a doubt, I'm not naive enough to believe that a character would NEVER, EVER, hit a customer, if provoked enough. And there are people out there that could provoke enough on purpose, to get a reaction.
As a PP said, I'm not surprised if we learned that this happened, to at least some degree, at CM regularly. Goofy accidentally hitting a guest while doing the regular napkin dance at CM is not an incident to me. Goofy acting incorrectly and accidentally hitting a guest is an incident. But in this case it sounds like Goofy was doing his role at the meal, not acting "goofy" or out of line.