The roadies messed up by putting the output of the amp (8ohms) into the 4ohm split into the cab. Played the whole show (1.5 hours). Is this going to mess up my Mark V head?
Probably not.
Duct tape. You could:
A) Cover any holes designated for non-use
or
B) Hog-tie roadies before committing them to the freezer in the garage.
Thanks MrMarkIII and screamingdaisy! This isn't the first time this has happened. I will certainly take your advice. I was ready to go out and throw down some more cash on another Mark V just in case.