I'm riding home yesterday and suddenly my bike starts running bad and popping really loud. Seems like its running REALLY lean. I reach down and pull the choke a bit and it stops. I get home and go to check the mixture screws and the right side is gone

I find the spring sitting on the engine case. Never had this happen on any bike before. They were adjusted about 3 to 3.25 turns. Any reason one would work itself out?