The disks on my car go orange when the rain splashes off the drive (or I wash it). If I haven't used it for some days, there's often a 'bang' as the pads free-off from the disks when I move off from the drive.

My wife's car can make an awful noise when toucnhing the brakes after being parked up for a few weeks (as happened last year). A few hard accelerate and brake cycles soon fixes it.