My brakes are pulsating lightly on the brake pedal lightly, it does not feel like warped rotors and brake pads?

are maybe 15% worn and rotors are thick with no groves on both front wheels and fluid is full. its a 2001 saturn and has 28,000 miles on it and gets driven maybe 3,000 miles a year if that,rotors and pads were changed 3 years ago supposedly. haven't looked at the back yet. just wondering if any one had any ideas before i just go buy 2 new rotors an 2 sets of pads? it only pulsates on the pedal lightly but u feel it, not steering wheel