did you adjust them with the weight of the truck on them?.
That is from the spring plate turning against the rod end. Those things are under tremendous pressure when you dial them all the way up static. Then you add double the weight of one corner of the truck do to leverage, and start turning things. One little burr can gall the aluminum.
I wouldn't worry about it, but if you ever break down your shocks might want to clean the rod end up. In the future jack the truck up to make height adjustments, if you didn't this time.