Worn-out Chickadee?

It was such a quiet morning when we were leaving to take Buster for a walk, that I was going to leave my bird paraphernalia; binoculars, bird guide, and camera at home.  But just as I stepped out the door, the cheerful song of the Chickadee caught my attention, and then it proceeded to fly up to the post of the feeder.  I went back in and got my camera and took this photo.  I was a little puzzled as to why this Chestnut-backed Chickadee looked so bedraggled.  My first idea was a juvenile, but they usually have a plump well fed look to them.  When I looked it up in my “Sibley Guide to Birds”, he shows a “Worn adult”.  I’m going with that.  In my mind I can easily imagine a worn out adult, tired of chasing bugs for its young ones, and tired of trying to get them to leave the nest and fly off on their own.--- Tired and worn-out.