Its probably your caliper sticking. I have the same thing with mine and by my caliper sticking that brake pad is going to need to be replace sooner so get the caliper replace soon as possible so that you won't have to replace the brake pads again.
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Exterior- stock painted black wheels, clear corners, stainless steel grill, cross and drilled front and rear rotors with evolution brake pads.
Coming soon- 18 inch black mustang bullet rims, GT/GTP rear bumper, tinted windows.