the expanding lipo! questions for the lipo gods

[Semi Pro]

so i have a lipo pack that is puffing alittle every time i use it, after its recharged and sits over nite is shrinks back down to its normal size.


is it really safe to run it?

i have never had a pack do this, is it normal?

what could have caused it to start doing this?

the pack looks like new, its never been in any crashes, and it has only been run 20-25 times,