I have seen incorrect rotors used. I have also seen the heat shields get bent and lock up the brakes.
Usually it is the hardware to mount the calipers is a little to long because a washer was forgotten and heat expands the rotor and will make up that small space and lock the rotors.

an aged

an aged flexible brake line between the connection on the inner fender and the caliper can cause this. Somehow the pressure in the brake hose fails to relieve when you lift your foot from the brake pedal. Enough pressure remains in that leg of the system to keep the caliper pressurized, and the pads dragging. I have seen this heat the rotor and wheel so hot that it melted plastic parts of the wheel cover.
Simply replacing this brake hose fixes the problem, although probably the rotor will have become warped and the pads ruined...

Would that cause a sudden lock up though? It seems like it would just cause dragging and wear down the pad.