I am former submarine battery electrician where we watched grounds very closely. I can say
You have your mind right to be asking the question.
Take a 5 or 10 watt lite bulb from each post (with batt cables disconn) and see if it lites. I think I would start with a 6V bulb and end up with a 1.2 or so V bulb (flash lite bulb?). I bet teh bulbs will not light so if you hooked up it would not be a problem HOWEVER it could be enough to bleed down battery over a matter of days to weeks.
I would bet your problem is more than likely acid tracking. Wash battery with soap and water to get rid of grease then baking soda water and rinse well with fresh water. NO soap or baking soda in the cells of course.
Dan Bentler
