Gens Ace lipo swelling after sitting?

[Thirdgen89GTA]

Today I had a bash session with some guys and I ran both my 3S twin packs, and my 2S twin packs down. The 3S packs were run in parallel, but I run the 2S packs in series for 4S.

Jammin X1 Truggy
RCM X1 CRT mount (18/62 spur)
MMM 2200kv
(2) 2S1P Gens Ace 40c 5000mah Hard Case lipos in series.
(LVC set stock @ 3.2v)

Since this was the first bash session I kept an eye on the temps. On 3S the ESC, batts, and motor never exceeded 110* (3S batts were 91*. on 4S after some wide open throttle runs when I brought it in the ESC was 130* and the motor 120*. The batts reported 108* and 110*.

However when I pulled out the twin 2S batts one of them was very slightly swollen! I left it on a curb with nothing but concrete around it till I was ready to go home. The swelling has gone down some and most people wouldn't even notice the swelling unless they placed the battery on a flat surface or compared it with another of the same batteries.

So i'm torn right now. A large part of me is rather upset, I've been monitoring the temps and its been nothing but happy to take whatever I throw at it. I really haven't bothered to throw many speed runs at it on 6S. At the tracks its been perfectly happy with temps on 4S and 3S staying below 110* for everything. I thought for sure I was using safe gearing for its main purpose which is bashing and track day practice.

The truck never flipped, or took a hard hit of any kind. It was all pretty much straight line runs and wide ovals.

Most of me is ready to trash this pack right now. I bought the packs to use in series, so if I trash one then I have to buy another 7.4V 5000mah pack of the same brand or I may run into issues.

Below are pics of the two batteries. Left is always on left, right is always on right.

http://home.comcast.net/~thirdgen89g...l/IMG_1725.JPG