Fatboy Brake Is A Drag

My 99 fatboy had me out for a ride the other day
up in the redwoods when I noticed I wasn't getting the speed i usually do
for the twist I was putting on.
Thinking it was some sort of brake drag I tapped my front brake,no prob.
I tapped my rear brake pedal and it SEEMED ok but the fat was not rolling smooth so I pulled over.
To my surprise the rear disc had started to blue. So I sat in the shade and let it cool off..... it seemed to roll ok so I rode home front brake only.
I am not a heavy rear brake user and this has never happened before.
I plan to get into it and maybe even replace the oem parts.
QUESTION IS does anybody know what would cause this brake drag.
all stock parts and 7500 miles.

Brake Drag

I experienced some brake drag on my fatboy. It was the pedal not properly releasing. I tool it into the dealer and they honed the bushing at the pedal and it works fine. I asked if it was common and he said it "It happens". It only happenned when it was warm.