Battery acid on garage floor

[gamer1]

I keep my 2002 pds Ezgo in the garage all year. For some strange reason I moved the cart to play golf yesterday and acid was all over the floor under the cart. Believe me once it has etched the concrete you don't fix it. Anyone have any ideas why this thing decided to vomit on my garage floor?
A few facts. (1.) I haven't recently filled the batteries. (2.) The batteries all have a safe amount of water in them...not showing any plates and no signs of acid on top or an sides of the batteries. (3.) The cart has not been moved for Approximately 2 months except for moving it out of the way to clean the garage. (4.) I did plug the charger in the other day when I found out I was going to play golf.
I now have a rubber mat under the cart.