Top of regulator has a rubber piece. While in cozumel on third dive.Dive op turned on air tank and it blew up like a balloon and popped. Any idea what would cause this? Had regulator serviced at authorized dealer before dive trip. Used the regulator for two more dives with the dive master keeping an eye on it. It didn't seem to effect the performance of the regulator. What is the purpose of that part? Do I need to have it serviced at a different authorized dive shop? Is it possible to send in directly to sherwood for repairs?