H3s have rigid calipers...not floating like most GM vehicles. There are no floating pins or rubber boots like a traditional caliper. So the caliper's ability to compensate for rotor runout now lies totally within the 4-pistons of the caliper...not the old floating-mount system. If you got pads wearing un-evenly...the problem is most likely with one of the pistons. The chance of anything sticking or binding is slim. You could have somehow got something bent, or bolted-on crooked...but thats not likely either.
My guess is improper bleeding. Because you have to separate the caliper halves to change pads....its possible that you have introduced air into the cross-over port that feeds the outboard (2) pistons. When you change pads...you may have had to push all the pistons back to their fully-seated positions to get the new thicker pads installed, right? Notice that when you push one piston in...the other pops out? It can turn into a wrestling match and its very easy to suck a bunch of air in there. If you lost fluid during a pad swap...this may be the case. Unlike the old floating single piston calipers...the quad piston units are very sensitive to air. Its possible that you got air trapped inside the caliper and you're simply pushing the bubble back & forth between the two halves. Try bleeding them with a reverse bleeder (introducing fluid at the caliper, and forcing any air back to the master cylinder).
To prevent this next time...first remove the lid from the master-cylinder and gently pry the four pistons apart (with the old pads still in place), before you take anything apart. The idea is to get all four pistons fully-seated and ready for the new pads before you separate the caliper. This will keep fluid loss to a minimum, and you'll won't be pushing on pistons while the crossover port is exposed to the air.
