I would think about all the different things I have done to front tires and associated components. First focusing on the Brake calipers and how they are aligned not the pads(is the tips of the moon shaped calipers coming in contact with the rotor or are they within a millimeter from the rotor. Then I would pull off the brake pads and check the caliper itself for leaking around the piston. And of course check the pad wear indicator to see if that is close to the rotor also.
To begin with.