ABS Sensor after rear brake replacement

I picked up the car from the Dealership and on the repair order the following description was provided. "Magnetic trigger on back of bearing has contacted speed sensor causing damage." I questioned the Service Manager and he provided schematics and the old bearing to show me were the sensor is located. I even asked if in removing and replacing the brake pad or turning the rotors could have had a impact on the magnetic trigger, they responded in the negative. I am always concerned of being taken advantage of because I am a woman and would appreciate any additional confirmation.