Hmmm any chance you might have drove over some kind of corrosive substance? fuel? maybe drove over a road that was about to be asphalted? It looks like some kind of chemical / corrosive damage.
I would take it back to the dealership and say you just now noticed it. Ask them to either give you a perfectly reasonable explanation as to why they should not replace it, or tell them they need to replace it.
Check real close to all the metal from the battery compartment down. see if there are any signs of damage that someone might have cleaned up.
Example, when the dealership put the bike together someone could have put it on a charger, over charged it, blew the battery then did a real good job cleaning it up, put a new battery in and all but might have missed what you found.
