[Walt Fricke]

Joe Bob gave you good diagnostic ideas:
a) At speed, when you step on the brakes, does the car pull?
b) Use an infra red heat gun (these are inexpensive, and are what places point at your forehead these days to see if you have a fever) on your brake rotors after driving around.

If it is just drag on one rotor, a) may not really happen. But b) will show up pretty clearly. If neither do, that might point to a problem with the MC, because if all the brakes drag, the MC is really the only central point. It isn't likely that more than one rubber brake hose is acting up, much less that all are. If the problem is isolated to one rotor, that would suggest replacing that brake line, and it only makes sense at that point to replace them all. I don't think it is guaranteed that original brake lines will necessarily fail. On the other hand, replacing them isn't a waste, even if it turns out not to cure the problem.