News to me...mine tend to get fully charged at the end of a club night, then left like that until the next week!
If it's storage state is so important why don't the battery manufacturers tell you this stuff when you buy them?
Personally, I'm getting more and more wary of listening to advice posted on forums about lipo's. Far too much here say, and too many chinese whispers for my liking.
I know everyone is trying to help, but there is too much conflicting advice, and not enough factual information provided by the manufacturers to back any of it up.
My advice would be to contact the manufacturers directly and ask them what they think caused it, and what you should do with them now.