Yes I have. some how the metal KD was making contact through the frame. So now I body mount couplers on older engines and us plastic screws on newer stuff.
I recently noticed an electrical arc from my track, actually near the frog points of an Atlas Customline #4, to a Kadee coupler pin. It did not shut the system (MRC Prodigy Wireless) down, but the loco (older Athearn switcher with older MRC non-sound decoder) just buzzed. Slight pin adjustment took care of it.
Anyone ever had this happen or have any thoughts? First time I think I've ever seen such an event.