Most times a pad may be loose and viberate as this is what causes most squeals.

Some times the noise will go away as the pad will jam in again and not viberate. That is why they put the pads on the back of the brake pads to dampen the viberations.

Brembo's on many cars are know for noise. Brembo brakes are not all created equal in quality in the OE sector. The Brembo calipers on the Camaro were squealing and they added lead tape weight from the factory to dampen the noise. They look horrible.