Tube burn up

[LesCarr]

I finished my brown sugar amp build and the amp was running fine. I even took it to a gig for a friend to play and everything was fine during the 2 hours it was being played.
I was playing the next day and the amp started distorting badly. I looked in the back and one of the power tubes was glowing red and blueish I mediately shut it down to cool and I replaced the tube thinking it was times up for the tube.
the second tube did the same. So I pulled the amp out and inspected and found nothing in the way of miss wiring obvious shorts or bad solder joints I cleaned the sockets with cleaner and trimmed wire that was a tiny bit too long and the solder lugs.The only things I found was some rosin and a couple flecks of solder on and around the socket and lugs. I've replaced the tubes and played the amp out of the cab and then let it idle for a few hours and everything seems to be fine.
What could have caused this could a component be going bad intermediately failing or was the dirt the problem.

[Enzo]

Maybe not dirt, but flecks of solder left over from the build process could have shorted tube socket pins together. And of course then pulling the chassis would have shaken whatever was on the socket down into the chassis. If it keeps working, then assume it is OK.

Everything works until it doesn't.