Are you using any case lube when you size? If not that explains it. Yes, it will stick and stretch on the way out. If you are using case lube that shouldn't happen. RCBS case lube is STP repackaged. get a stamp pad and a bottle of STP if you don't have any case lube. If you have lanolin in almost any form, snow seal, bag balm, or oilskin treatment it will work just as well and soften your hands at the same time! STP wipes off easily with a rag, just a little lanolin I just leave on.
Since you are shooting a solid revolver I'd shoot it. After shooting it I'd pull the case just to see if it split and if so where the piece of brass went! That being said, I'm curious and an experimenter. I was 16 when I got my Lee Loader, I realized the potential for popping a primer so I went ahead and deliberately popped a couple so it wouldn't surprise me when it happened accidentally. If you are not, pull it.