faulty throw-out bearing

I own a 2000 mustang gt with a t-45 tranny. Recently i had a king cobra clutch kit installed and after about 2500 miles the throw-out bearing started making noise. My mechanic replaced it and also installed an frpp clutch quadrant and firewall adjuster. He adjusted it so the throw-out bearing is never spinning unless the clutch pedal is depressed, yet within two weeks the bearing was making noise again. I suspected the bearing retainer might be the cause, but it's a steel retainer and he said there was no sign of galling or distortion. The only explaination he can think of is that possibly they had a bad batch of bearings that didn't get properly greased or something. If anyone has had the same issue or knows a possible cause, any suggestions would be greatly appreciated.