When you say, my front brakes, did you mean front wheels? As in steer axle? If that is what you mean t, I'd be looking at the master cylinder. You could have one wheel start to lock up, that could be a caliper hanging up and then overheating. But if both are dragging badly, I'd suspect the master. The master has two pots one for front and one for the rear. When applying the brakes I believe on our coaches, they engage just like a P 30 chassis.
When this happened, did you feel the front hubs, to see if one or both were really hot.
I'm not sure, but maybe the brake line off the master that goes to the tag axle controller under the dash could be causing a problem. But I don't see how it acting up could back feed into the master cylinder. DJ