Well you have a common problem. You may have a glaze buildup on the pads. Two schools of thought. Replace with a different material ie, newer carbon fiber-metallic blend, or do a couple of full tilt boogie panic stops (using common sense and safety) to try and burn glaze off. This usually helps for a while, but it eventually may come back.. This can be a pain in the butt to get rid of sometimes.
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.