[joyridin']

From what you described in your original post, it sure seems as though the rear brakes are out of adjustment. The GM calipers use a ratchet mchanism and sometimes, you can just be on the edge of it clicking, which will move the pad closer to the rotor and your pedal will be high. I have literally done a hundred brake jobs with these style calipers and probably half of them end up with the situation you describe. This is of course assuming there is no air in the system .