My trusted SE has a recurring problem with the right front axle. Around 60k and again at 80k and 100k the axle nut, the one that holds the axle to the spindle, worked it's way loose. The axle has never been removed. Each time the nut was torqued to factory spec (not by a dealer but by a reputable and professional private shop

.
Symptoms were originally a mild rumble, very similar to driving on rain grooves, getting progressively worse. The next two times it was a knock as if something were loose (which it was). After tightening the nut to factory spec (200 ft. lbs. I believe) everything was fine until the next time.
Now that it's been about 10k since the last time I'm getting a very brief noise very much like a small stick was dragging in the axle, but it only happens after sitting several hours and only lasts for about 10 secs. After that all is well.
I'm inclined to replace the entire axle but am not convinced that's the solution, especially since the whole issue is so intermittent and temporary.
Any similar experiences out there?