light wear on the rear is normal. It's a good idea to remove the drum on the rear, when changing the front pads, to clean the dust out and lubricate the adjuster. You can also manually adjust your back brakes by turning the adjuster a little at a time with a screw driver then try to slide the drum back on. Do this until the drum slides on with a little drag.(do both rear drums the same) This will give you better braking and less pedal travel.You can also try to make the adjusters work automatically by going in reverse and sharply stopping, Do this a few times and it should adjust the pads for you. I have found the best way is to do it yourself, this way you can inspect for any other problems that may arise in the future.