I hear a sqealing noise from my brakes. I have inspected all and see nothing that could be causing this. Rotors are good and pads were replaced 25,000 mi ago and are good. Any ideas?

Many aftermarket brake pads are not compounded the same as OEM. This is one of the primary causes of squeal. Also, make sure the caliper pins have been cleaned and lubricated with silicone grease or Squeak Relief (silicone grease and moly). Many aftermarket pads don't come with the shims that came on the OEM pads. These shims need to be properly coated with anti-sqeal compound or Squeak Relief.