What happens when the wind starts blowing through the tree house in Chapter 9?

As Tully climbs up to the tree house to get it ready for Donna Kay, the wind suddenly kicks up. Ix-Nay has told Tully that wind without noticeable weather means the spirits are talking. Tully hears the voice of Johnny Red Dust telling him that in order to continue his journey, he needs to tell Donna Kay what really happened in Wyoming.