I mean the pins on which the whole caliper slides, they don't work particularly well at sliding and so actually jam in place as you apply the brakes.
Theory dictates that for every action there is an equal and opposite reaction, ie the pad pressure should be equal on both sides of the disc, they never are, I have eyet to see a set of pads with pin sliders where both are worn equally, the only thing that could cause this is sticking of the pins.
In addition developing a taper on one pad is not that unusual either.
Clean the pins off and use SILICONE GREASE on them.
tabetha