I've got 2 new lipo's that swell slightly when fully charged compared to when not, but I have had a lot slightly swell, is this bad? I'm talking a movement of about 0.5m in 26mm hardcase packs!?

If they swell and then go back down, no, that's prob not bad.

The real quest is why are they doing that? They shouldn't be that sensitive.

Are you keeping them fully charged between uses - storing them that way for a week or more?

Nope, they came to me at @3.8v each, I have cycled them a couple of times but never let a cell get below 3.3v and always stored back at @3.8v again. Haven't used them in a car yet and getting a bit nervous, if I keep cycling them and it doesn't get worse should they be ok? The cells behave fine when charging in terms of no funny things going on!?

When cycling I am discharging at 10A by the way, they are 5400 cells and with more than 4000 taken out of them begin to get warm!

Any ideas on a cause!?