Something is wrong because something burned. You should absolutely open it up and inspect it. Do you use the amp differently in any way at home than you do at a show? What's the difference? You could try to recreate the problem, but I would open it up instead.
Three things... Those amps are notorious for blowing filter caps. You may not notice the difference right away. If the bias supply went kaput your tubes would be running too hot and you may not notice right away. If a power tube blew the amp may still operate somewhat normally at lower volumes and you wouldn't notice right away.
I'm sure there are a host of other things that you may not notice right away. But if you smelled something burning, and a fuse blew, something inside blew up or burned up. You have to open it up. For the sake of safety if not for your own satisfaction.