I have owned 2004 vti oriel, from the past few days i am experiencing that after driving the car for about 15 to 20 km, my brakes performance goes down specially when i apply slow pressure on brake pedal not sudden. The pads physically seems ok. braking fluid is also up to the level. What would be the possible causes for this issue? Please note that this issue not emerges from the start but after some KMs of driving.