I went to my dealer today and asked them what the white stuff in the coolant overflow bottle was. The only thing they were able to come up with is that when antifreeze dries up it crystallizes. It probably dries on the radiator cap and then is washed in to the overflow next time you ride. I was told not to worry about it that it was normal. Just keep an eye on your temp gauge but it shouldn't be a problem.
I checked the overflow bottle in my truck and it had it too.
I checked the overflow bottle in my truck and it had it too.