Stephen King also went back and altered 'The Gunslinger' to fit with the later Dark Tower books. The original can be found on ebay etc so it's not a massive deal, and the Dark Tower series is so awesome that I'm glad the first book now fits, but still... it's very much George Lucas territory - he wrote the first book, which spawned a sequel and ultimately a 7 part epic, so went back and 'fixed' the earlier work to fit later ideas.
P.S If you haven't read the Dark Tower, read it now.