So who replaced the pads that had only 10K on them? If they didn't re-adjust/check the E-brake correctly, they caused the premature wear.
As far as the self adjusting on the rear disk brakes of of modern Dubs, there are 3 things to consider.
Hydralic: ALL disk brakes compensate for pad wear by keeping a very slight residual pressure in the system so that when you take your foot off the brake petal, the pads are still just barely touching the rotors.
Mechanical: (E-Brake). There is a ratchet in each caliper that compensates for pad wear for the cable applied part of the system (The ratchet is the part you have to screw in when you replace pads). The ratchet ratchets out to compensate for pad wear through the action of applying and releasing the E-brake.
There is an adjuster to compensate for cable stretch located at the E-brake handle.
If the cable adjuster (at the handle) is adjusted prior to appling first the foot brakes and then the E-brake several times, after doing a brake job, the ratcheting adjusters, at the calipers, could make the rear brakes drag after you use the E-brake a few times.
To check to see if the cable is adjusted correctly (Bentleys):
Apply foot brake forcefully 3 times.
Apply E-brake 3 times and release.
At each caliper measure the distance between the little arm the cable hooks into and the stop that it comes up against when the E-brake is released. The dimension should not fall short of 1MM or exceed 3MMs.
Spin each wheel and make sure that you cannot hear any dragging of the rear brakes.
Due to the automatic brake adjusters (ratchets), there is no need to adjust the parking brake after making the initial (cable) adjustment.