Looked into it today and found that one of the caliper guide bolts backed itself completely out of the sleeve. Since it was the bottom caliper bolt, the bottom of the caliper was resting against the rotor. I contacted Ron at PerformanceTrailerBraking and he is sending a new bolt. He said these have a tendency to back themselves out, and to use Loctite the next go around, which I will add for all of the guide bolts. I'm not convinced it was torqued correctly to begin with, but Loctite and retorquing to the proper spec should keep it from repeating itself.
300mi home today averaged 8.1mpg, I've made the same trip many times and usually get 10mpg or so.