I have finally figured out what might be my problem with mileage... the hard pipe to the caliper was bent funny to the rubber holder on the fender, and I think it was acting like a spring and holding the pad to the rotor. Derp.
Now that I have the holder bent out of the way so the top of the pipe sits freely, whenever I hold the brake lever, I see fluid seeping out around the pipe at the connection to the caliper. Not coming through the threads, but in the middle of the nut around the pipe. The nut is nice and tight.
I figure it is probably a crack in the pipe flare that is allowing the fluid to seep out. I'm not riding the bike until I get it diagnosed.
Anyone else have a similar issue/solution?