Hi-- With regard to my new Glock 20 S/F and my Glock 29, when disassembling the guns, when I pull the slide off of the receiver I note that the back end of the recoil spring assembly comes up and out of its seating notch on the barrel lug. It doesn't fall out of the slide but re-indexes higher up on the lug. Is this normal? Any thoughts. Thanks, Semper Fi.