Potential Brake Problems

Okay, I recently installed 1" aluminum psacers on all 4 of my tires, everything was fine for the first few days but now when i break there is a very slight creaking noise coming from the front end. it makes no odd noises when i drive or any thing else and dosn't do it all the time. Any Ideas / Similar eexperiances. taking it by the dealer as soon as i leave work today to have them look at it.