Problems with new brakes wearing unevenly

About 2 weeks ago I replaced the rear pads and rotors on my 2004 Mazda3. I just now noticed that the brakes arent wearing like they should. Judging by the surface rust thats accumulating on the rotor only the outer half of the brake pad is actually touching the rotor. The inner half doesn't seem to be touching the rotor like it should so the rust never comes off. I dont mean this like the inner and outer pad. I mean on one pad only half of the pad is touching. This is more pronouced on the right than the left. What can cause this and how do I fix it?

How many miles have you driven since installing the pads and rotors? Did you follow a brake pad bedding in procedure? Here is a link for the Tire Rack disc and rotor bed-in instructions.
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=85

If you still have the problem after driving the required distance and bedding-in you may have high sports on the pads. You should be able to remove the high spots with some coarse sandpaper. Attach the sandpaper to a smooth surface at move the pad by hand to even the pad surface.

Clifton

Sounds to me like the pads aren't seated correctly in the caliper. New pads should have come with anti-rattle material riveted to the caliper side of the pad. Check to be sure a rivet or some foreign material isn't keeping the pads from seating tight against the caliper. Maybe some aftermarket pad maker put the rivets in the wrong place.

I don't have a 2004 so I can't post actual processes.. the 05/06 Factory Service Manual is available for download off my webpage.