Very recently, I've heard a grinding noise for the first stop or two after an hour or two of non-use. Pads and shoes have adequate lining, drums and rotors are not gouged, no leaks. The rear shoes appear to have more wear than I would expect, but I could be underestimating use and miles since the last change. Left front brake had far more wear on the outboard pad than the inboard, but it wasn't worn to the squeaker yet. The sleeve at the retaining allen bolt was very tight, not able to slide evenly, probably accounting for the uneven wear, and I'm guessing unrelated to the other problems..
Any idea what might be causing the premature rear lockup?