When washing my truck, I found one of these laying at each wiper arm. I am guessing it it used to index the arm to the correct orientation. When I re-install them, there is nothing to hold these pins in place and they just drop right out. Is this normal? Do I just hold on to them for when arms get removed in future?

 

You can throw it away or put it in your tool box.
Used on the production line and not needed any longer.