More likely the freshly-charged battery was warm enough to heat up the air inside the canister. The expanding air put enough pressure on the o-ring to extrude it, allowing water into the can.
I've seen that happen ... which is why you should always make sure your battery is cool before sealing the can ...
... Bob (Grateful Diver)
Possibly, but this was a lot of extrusion. I wouldnt have thought expanding air would have pushed it out that far.