The calipers could be getting sticky and not retracting
(My left front does this every once in awhile, need to take it off and get a freebie (lifetime warranty))
Usually only 1 will stick. Take your hands off the wheel and see which way if it pulls. The side it pulls to is usually the good side (not overheating and braking ability). Also the bad side will probably have more brake dust.........
Braking force is a product of the ratio of the areas of the calipers vs master cylinder bore size. A larger bore gives you a harder pedal (more leg needed) with shorter travel. A smaller bore is easier on the leg, but more pedal travel.
You also may have boiled some fluid due to sticky calipers which will make things mushy.....
