DMOZ recently changed its canonical URL from http://dmoz.org/ to http://www.dmoz.org/, so Google is now re-resolving all the URL’s there. Sometimes pages on a website get lost when a site “fixes” its URL. (DMOZ used to be available at both URL’s, but only recently 301’ed all of its URL’s to the www. version.)
Like most things related to both Google and DMOZ though, there’s not much you or I can do about it, so it’s probably not worth stressing out about. Nice to see Google finally update the Google directory though.