Glad to be of some assistance.
I wouldn't bother with the vet myself; very few of them know much about chickens in general and very unusual conditions in particular, viruses can't be treated with antibiotics, and it would appear that whatever your bird had, he has since got over it, so no...
retention of the sheath like that is affecting one of my birds too, a 5 year old roo, who developed it after a serious infection of some sort last summer. I haven't yet found an explanation for it. A particular virus causes this (amongst other things) in Antipodean parrots, but that's probably...