The OP has already checked for injuries, it doesn't sound like that's the issue.
I'm not sure I can give much advice on what Mushu is doing, I don't have too much experience with males or multiple hedgies. It does sound a bit like mating behavior, maybe he's just a little overexcited to see another hedgie, even if they're male?
To be safe, it would probably be best to go ahead & keep them separated, just in case either of them gets overambitious and to try & keep Mushu from getting too attached. One of the other mods or people with more experience with males & multiple hedgies might have some better advice though.