since quite a few posts cross over to each other (ex: WC forums, SD forums, JoeUser, TGN, etc) once in a while a spambot will get in somewhere, cause the post to rise - the reply might get deleted but the post is still in view as if it were new.
I've seen some posts revived that were over 2-3 yrs since the last activity.
some by bots, some by noobs