Luckily the gas had only been on long enough for us to realise we had a problem so no explosion. Hard to say what had caused it as the pipe is new and no sign of it perishing. Last time we were out we packed up in a hurry and must have left something digging in to it or pressing on it. We'll watch out for it in future. Incidentally our bottle opener/corkscrew proved the perfect tool for screwing the connector back on.