Brake noise

I got back from a long trip (~2500mil), and during the last 100 miles, when I would apply the brakes I could feel something grinding in the front end. I felt it through the brake pedal, not normal. :( During normal driving without braking all was well, so I think, brakes are bad. I now at this moment have the truck on four jack stands and have the front pad off. THey have about 50%+ of good pad left and the rotors look great. :confused: I'm going to take the rear pads off and look at them, but all the noise was coming from the front.