TheJon
I have a particular pair of jean shorts that, for whatever reason, always gets something gritty in the joints of my knives when I pocket them. I've laundered them a bunch but it just won't go away (the shorts, not the knives). Have you noticed this phenomena with anything else? If that was your sole carry knife, it might be hard to sniff that out. (I realize the low probability this is your sole carry knife, considering the forum and the people who gather here, but it's worth a thought.)
My #35 would "catch" kind of when I was closing the blades for a while, but recently I've noticed it's gone away completely. I've had it for ~2.5 years.
I'm sure this is nothing new to you, but my strategy for flushing a knife uses dish soap in the joint, working it back and forth, then under luke warm water while working the joint back and forth. Finally it's a trip to the air compressor to blast it dry thoroughly. oil liberally afterward!
Good luck!