The original filenames had apostrophes; "kt's_furry_faq" instead of "kts_furry_faq". The problem with this was that LiveJournal would get messed up. You know how you can just drop a URL into a post, and LJ will make it a link? LJ thought the URL stopped at the apostrophe. No good. And since I consider my Furry FAQ cartoons very useful, the breakage of this autolink feature was enough of a problem that I decided to take out the apostrophes.
The old apostrophed-up files are still in place, to keep old links on other sites from breaking, but each one includes a note saying it's deprecated, with a link to the new version.
(Edit, Oct. 12, 2006: When I moved my site, I did not move the old versions of the files. I figure that's been enough of a grace period.)