If you didn't see it, Jetboil has announced a recall on burners that went out to distributors in 2008. They have three types of burners, and one of them has a thread problem that can allow gas to leak and pose a fire hazard. If you go to their website at http://www.jetboil.com/, they have photos posted so you can tell if yours is affected.
I checked, and I have a bad one. I filled out their form online, and in about two days they sent me a pre-paid, pre-addressed box to put my burner in to mail back for exchange. Really simple -- just put the burner in the box, stick it in the envelope, seal it, and drop it in the mail.