I also looked at the used rotor and noticed that there are pad marks on the outside, but not the inside. I wonder if the caliper is not releasing on that side when I let off the brake when I park?
Pics of the pads are also attached. The top one is the outer pad, which aligns with the pad marks. It seems to show a bit more wear.
The Zimmerman FAQ made me certain it was a bedding issue.. but now I'm not so sure. I could use some advice here. If taking it to a shop would fix it, I would. But I'm guessing they'd just sell me more rotors and pads.