I can see that riding "for two hours" with the parking brake on could warp even a heavy disc. Pads must have stunk, too.
I was getting my flat tire replaced on my Forza 300 one day. I noticed a tech working on a scoot like mine and wandered over to ask what he was doing. "Replacing the disc. Rider rode for miles with the parking brake on!"
This made me aware of the damage, (not warrantied) that I could cause if I were to make the same mistake.
Stig