Does it PULL under braking? Is one wheel warmer than the other?
The front brakes SHOULD be doing a lot of the stopping, so compare front to front.
If the calipher is binding, you may be wearing an the outside lining more rapidly than the inside.
Put it on jackstands and pull the wheels; you should be able to see the upper end of the lining with a good light; are they worn about the same?
Good luck; if it is unusual wear, the warranty should cover it.
'04 Rubi, manual, usual options, Hella H-4s, any range lockers, Randy's booster seats, Oly pushbar, 245/75R16 BFG
'09 Audi A4 Avant- my bride's schnellpuffenpanzer
'12 Ford Focus-the sure way to get good Jeep mileage
'07 Dodge Caliber R/T AWD-da kid's ride
Goodbye Old Blue XJ; 10+yrs, 100K+ miles; virtually trouble free; Long may you run!