The Blanket

At what point is a blanket ready for retirement? According to Big Man this blanket is still perfect. It was once his duvet cover that he continued to want with him when he moved to his bigger bed. There is only one spot on the blanket that he wants to hold and that is the knot. I can hear him sometimes at night looking for "the knot." He will be saying Where did it go, I can't find it, Oh there it is. Then he will go back to sleep. I don't understand it, but whatever works I guess!