Couple options here. I agree with your dealer in that gas is filling up the crankcase. I had it happen on my 04 V2 as well, bujt only when I trailered it with the fuel pet cock turned on. I turned it off when trailering after that incident and had zero problems. So, with that said, it wouldn't be a bad idea to turn it off if you're planning on leaving it sit a while.
Another thought is that you could have some crud in the carbs that is preventing the floats from seating fully, which causes more fuel to trickle into the carb, fill it up, then go into the cylinder, then down past the rings into the crankcase, thus filling it too far.
Those would be my two starting places.