Water vapor is a normal by-product of combustion of gasoline. It's just not too normal to see it coming out of the exhaust, unless it's cold or really humid outside. I've seen water drip from car exhausts fairly often, so no big deal, unless it's the color of the coolant, then it needs to be looked into.
One other thing, when you first start the bike, some of the water vapor condenses out against the cold metal. As the pipes warm up, it becomes less and less likely the water vapor will condensed out before it is expelled.