It's a good case of pathetic-fallacy anyway:
Dean and Sam start their talk...the trees across the water are full and the sky is blue.
A couple of sentences later and the leaves have all fallen from the trees and the sky is overcast.
In other news, I've been waiting to cap Hunted because of this icon I want to make - but sadly, the cap I thought I could get from it wasn't as good as I thought...so, sigh...if anyone has a really good cap/picture of Sam smiling, let me know. I wanted the kind of soft smile that he gets when he's thinking about how much he loves Dean.