Not an expert on Shingles but I would also think that it isn't necessary to actually come down with chicken pox at a younger age but simply be exposed to the virus. I've never had chicken pox (at least visibly or that I know) but as a kid was exposed to it through my friends and I even babysat my niece and nephew for several days when they had it and I was about 30.
That said, there is a shingles vaccine now for those over 50.
edit: digging around it seems there is a further elderly disease/condition being linked to the virus (very preliminary research). Inflamation of blood vessels which can sometimes be fatal.
http://www.cbsnews.com/news/chickenp...on-in-seniors/