I had the brass fitting where the gas line turns up in the rear for an outside grill crack. Same results as you, lost a bunch of propane though not as much as I discovered the problem at a rest stop (smelled the gas) and turned the gas off. There was a dealer within 30 +/- miles so we pulled there and they got right on it and replaced the fitting and refilled my propane tank for free as the trailer was only a year old and still under warranty. I asked if they'd seen this happen before and the tech said "yep, worked on about half a dozen so far with the same problem" (this was last year [spring of 2009]). So far I haven't experienced any more trouble but if I do the entire line going to the rear grill will be removed and capped off, if possible since I don't use an outside gas grill. All that may well change especially having just said I don't use 'em.
Here's hoping you don't have any further trouble either.