I had a couple of 1S cells I carried around 'just in case' but didn't use for the better part of a year.
One is fine and was recently charged and raced on a club night. Apart from being a tad off on top speed due to its age, and technology having moved on, it was fine. The other one went flat - totally flat, as in 0v - and puffed up a bit during the same time period.
I would suggest that voltage on the stored cells is checked, and if it drops below 3.2v then a quick charge/discharge cycle would be in order. I've had the same problem with receiver packs - one went flat the other two didn't - so it seems to a be a bit of pot luck. A regular monthly check would avoid any problems during storage. Storage itself doesn't seem to do them any harm from a performance perspective. HTH
