I completed a brake job on the front of my 02 TB. After a few months, the brakes started squeaking. I did not use any anti squeak compound on the brake pads. I have done brake jobs on cars for 20 plus years and have never used the anti squeak compound. Until this brake job, I have never had the brakes squeak. Two questions: First, what causes the squeak. And, can I put the anti squeak compound on the pads or is another brake job in order?