I just installed new front rotors, Hawk HP+ pads, stainless lines and bled the brakes. I was driving and then I could feel the brakes dragging pretty bad and the pedal got extremely stiff. I guess I wouldn't expect this from having air in the lines, so what would cause this?

I parked the car as quickly as I could and took the wheels and pads off and let everything cool down in an attempt to keep the rotors from warping. I'm guessing I ruined the pads, which sucks. I had to crack open the bleeders to relieve the pressure though, it was that bad.

 

well the square cut seal is suposed to bring the piston back in when you let off the brakes but yours sounds like they locked.

 

I'm not sure what you mean. If you are talking about the floating pins that hold the caliper to the bracket, they were not frozen. The calipers are brand new. There was too much pressure in the lines somehow.