I also keep mine in an old cast iron dutch oven, but that dutch oven sits on a bed of sand inside an junked out gas barbeque grill in an outside shed. Unfortunatly thery are subject to outside temperature variations.
Years ago an old Fireman told me that charcoal bricketts could start fire by spontantous combustion if they were exposed to too many cycles of drying out and re dampened while in storage. I wasn't sure if he was pulling my leg, but now I wonder if LiPo's could do the same. Chemistry is funny.