Running CJ outers up front with CJ discs and Scout calipers. This is a relatively recent change when I installed high steer, but the same problem has persisted prior to this change (CJ calipers).
What exact rotors & calipers?
With CJ calipers you *could* be running mismatched caliper/rotor. Early style 1.125" wide "Big Brake" rotors (circa '77-'78 Scout/CJ) as opposed to the .875" late model rotors (which everyone ends up using because they cost 1/2 what the early rotor does
The symptoms I've seen from folks running a combo of early (wider) calipers on late (narrow) rotors is usually reduced braking performance since the pistons are nearing the end on their travel and never seem to clamp tight... this could cause some rotor overheating (like a sticky/dragging caliper) I guess?
My D30 disc conversion has some pics of the CORRECT Bendix calipers/casting#s for the early 1.125" rotors if needed for reference...