Noise when turning right, after replacing rear rotors

Any idea is appreciated.

Hi,
After I had my rear rotors replaced, I can hear a very obvious "noise" (like the sound made by scratching two pieces of metal) WHEN MAKING A RIGHT TURN. Otherwise the brake works well.
I went back to the auto repair garage, and the mechnics (after drove my car and replicated the noise again) told me that it is because "the dust shield is a little bent".
Is this explanation belieable? Or, any other possible reasons?

Any idea is appreciated. Thanks.