Do you mean squeal. You describe a light screeching. If you mean the squealing sound then if the brakes are not brand new you've got a buildup of the binder resin on the pad faces. You can go to the dealer if you want, but, they won't make any adjustment b/c brake consumables are not warranty items. Take it out on the highway and of course observing any and all safety considerations (Hi Deezel) get up to your normal cruising speed (whatever that may be and make a couple oh hard stops. The idea here is to burn off the resin buildup. Depending on your driving style the time it takes to return varies. Replacing pads sometimes helps, but MBZ seems to have a pad composition which lends itself to being noisy.
1987 BMW 325