replies to threads older than N days sent to moderation queue

Hi all, I have been searching through the site and not seen any mention of this... so I suspect that it will require an addon to accomplish (though I have a nagging feeling I've seen it somewhere)..

Rather than locking old threads altogether, I'd prefer to show the user a message near the reply box that tells them that it's old and that their post will be reviewed to determine if it's appropriate. There is a mod that will warn the user that it's old, but I've seen nothing about forcing review.

Am I missing an option somewhere?