Brake noise

Could be the incorrectly fitted bolts backing out, some gravel, or the brakes simply not fitted properly.

If the car is parked up a lot in damp weather (UK this summer?) then rust will form on the disks.

The first time they are applied you will hear this being ground off.

This will be more noticeable if the brakes are applied when running slowly and in reverse (e.g. after backing out of the garage).

Diagnosis - correct operation, although you could be getting near the end of the pads.

Thanks. I think I will take it into the shop. However, the weather is not damp here at all (no rain from April through Sept./Oct. And given there is only 12500 essentially highway miles on the car I hope I am not at the end of the pads already.

Since the problem corrects itself it cannot be the bolts or incorrect fitting of the brakes. And given it happens all the time I would assume it is not some gravel.