Finally got around to checking AC clutch gap. (FWIW I have only had the problem twice since original post).
I also tried the flushing water over the condenser while the problem was happening (no change)
Gap is difficult to measure accurately while in the vehicle, but best I can tell, .035 is a little loose and stacking a .035 and a .005 is getting tight.
From the research I have done, it looks like .030 is max gap. Perhaps 5-10 thousandths is enough to occasionally not pull in the clutch under certain conditions?
Debating on just trying to do the shim modification, vs clutch and coil replacement, since I will likely do some tear-down to get to it more easily. Then comes the bigger debate of whether it is worth just replacing the clutch and coil, since it is almost as much as the entire compressor, but then I need to drain down the system, change the accumulator, recharge....where does it end?
I think this comes down to whether the clutch gap is more likely the problem or if the coil is more likely the problem.
Leaning towards trying shim modification 1st, since that is only time and will help rule out gap as the cause.