The pads constantly ride on the rotor.
The noise you are hearing is the heat shield rubbing against the surface of the rotor. Especially if you just replaced the brake pads, it tends to happen every time.
The heat shield which sits right behind the rotor just takes a bump and it will scrape the rotor. It is tough to straighten them out becasue when you bencd it on one place, it tends to bend the opposite way on the other side. It is especiallty hard to clear the area on the front rotor between the lower ball joint and the rotor. Its a real tight fit.
So, take some time and check the clearance between the heat shields and the rotors. Even if it is close it probably scrpaes when moving as the shield moves some and the suspension movement will load it and move it a few millimeters. Eventually you will get it straight and so it ASAP as it is not good to groove a rotor. It will eventually make it shutter if the groove gets bad enough.