After about a week away, I've finally been able to inspect the wheel, and why it was 'locking up' (sorry for the very vague phrase).
Well, the axle appears to be bent... very slightly. Normally, this shouldn't cause a problem or be enough for the wheel to ‘lock up’, I've ridden many miles on bent axles, even on broken axles, when forced to. The dust covers, made of aluminum, go out over the wheel nuts, so there's maybe a 1/16" from the end of the dust cover to the surface of the wheel nut that goes against the frame. Also, the clearance between the wheel nut and the dust cover is very tight, as you can expect.
When I took the wheel off, the dust cover, which is independent of the axle assembly and screws into the hub, was not seated in the threads, but crooked, and rubbing against the wheel nut. When off the bike the axle can spin with some minor friction, but with the wheel tightened down in the fork, the wheel does not move without a great amount of force, most likely due to the dust cover being jammed between the fork and wheel nut. I removed the dust covers on both sides and the axle spins freely. I reinstalled the dust covers into the threads but the wheel nuts on the bent axle hits the dust cover on one side causing enough friction, I guess to push the dust cover out of it threads with enough riding.
About three weeks ago I installed a front rack on this bike and have been carrying fairly heavy loads front and back; 5-6 bottles of juice, milk, potatoes, etc. I am also a bigger than normal rider, between 215-225lbs. although the bike is only ridden on the road, never jumps curbs or abused, and basically a commuter and grocery getter to replace my car. I can only assume that the extra weight on the front end caused this, after 7 or so months of trouble free operation.
So, a bent axle, obviously any one who can take a wheel apart isn't gonna get another wheel from the same place, not worth the time or the effort. I'll probably get to the LBS sometime this week and buy myself a nice new harden steel $10 axle. Heck, maybe one for the rear too. And start looking to build my self a nice new set of wheels.