Parking Brake Related Problems of the 2007 Mitsubishi Outlander

Parking Brake problem

While driving my 2007 Mitsubishi Outlander the right rear brakes locked up and wore down the brake pad to nothing causing metal on metal contact with the rotor. I contacted Mitsubishi and had the vehicle towed to the closest Mitsubishi dealership. The mechanic at the dealership told me that the emergency brake cable had adjusted itself causing the brakes to do this. I questioned if it was a mechanical failure so it would be covered under warranty and he said no. Mitsubishi replaced the rear brake pads as "good will". I'm concerned that there is a defect in the emergency brake system. And what is going stop it from "readjusting itself" again. I believe that Mitsubishi is lying so it can save money on not recalling all Mitsubishi Outlanders and putting my family in a dangerous vehicle.