The term "Windfall" comes from Apples which are knocked from the tree by wind, so you can just go and pick them off the ground and sell them without having to go to all the trouble of picking them.

So strictly speaking, that value was always coming your way you just received it early for less effort than otherwise. Unless you're scrumping that is ;-)

Not sure how this ties in to our metaphor here but it kind of feels poignant.