So, I'm kinda new to the NFA world. Got a can from Dobbs and love it. I've shot it now at Quickshot and OA. The RO at OA stopped me while I was loading and requested to see both my stamp and my can to match the serial #. Is this common at ranges? This was my first (and most likely my last) time shooting at OA. Am I being tinfoil hatish or was the RO throwing his authority around?