I have had 2 motor homes on Chevy chassis, 83 Winnie and 89 Southwind.
I had problems with brake hoses on both.
The hose fails internally and acts as a check valve and won't let caliper release.
When yours was sticking it overheated the brake fluid and caused your problem.
Once it cooled off and you pumped the peddle back up the pressures came up and canceled the brake warning light.
The hoses should be available over the counter at most parts stores but you need to match them up with old when buying because the bracket for bolting might be different.