Thanks everyone. I called my shop and they told me I am not the first person this has happened to. He said in their pool classes, students frequently forget to put the cap back on before rinsing (of course these regs are never exposed to salt water, only pool or fresh). He said it shouldn't mean my reg is ruined, the bigger issue would be if I got salt water in there. I know I have hosed it down with fresh water after diving in salt, so it's possible some got in there. I'll probably take it over for them to check it out anyway.