I jacked up the car to have a look at the brakes. The RR one was definitely badly stuck. I loosened the bleed screw and it didn't release, so it wasn't a swelled hose. I got the caliper pried off the car and found that the pucks were very sticky, a bit rusty. I drove the pucks out (serially) using a C clamp and the brake pedal, then I cleaned each bore and puck with wet and dry 600 grit sandpaper, sluiced out that side (there was a fair bit of grunge in the caliper) using brake cleaner, lubed the puck with brake fluid and re-installed the puck, which slipped in easily once it was cleaned up. The rubber boots were still intact, and were no problem to reuse. In essence this was a brake caliper rebuild, except that I didn't use new rubber. The old seemed fine, the problem was just rust buildup from having sat so long. There was a bit of a ridge on the outside edge of the brake disc, preventing easy removal of the pads, so I put the car in gear and then took a grinder to it to lathe off the ridges. The pads themselves looked like they might be nearly new, they were very thick. After putting it back together I bled that brake and then took a test drive. Much better, you could tell when coasting downhill that there was much less drag. No heat on the hub either when I got back. Progress!