Sometimes the front brakes on my S70 T5 make a rhythmic clicking noise that is felt through the pedal, as though some flexible metal finger is hitting the spokes on the wheels, or something like that. The rhythm doesn't seem to be in sync with wheel speed, or degree of urgency in braking. The brakes function fine, the pads and rotors are fine, and this noise only happens sporadically. Naturally, it won't perform for the dealer's service department. Anybody got any idea what's causing this and is it anything to worry about? Any ideas/suggestions would be appreciated.