I have 3 different LiPos and I've yet to have any problems with them, but I know there are certain risks. I always store them in the sack when not in use. When I charge, I always keep and eye on them. Paranoia? Maybe, but ask the guys who've lost their house or car (not the RC one) to a LiPo fire if it's paranoia. I look at it like this: a bag costs $20. It's pretty cheap insurance and it adds 3 seconds to your charging/storing procedure.