After doing some reading, I believe my amp is overheating. I use a Warwick FNA Jazzman 5 & Darkglass AO 500, going into a Mesa Boogie PH 1000 4x10 + 1x15 OR Fender Rumble V3 4x10. I am the second owner of this amp, and it is well over warranty at this point.
After some use, usually around 10...