What's happened is that there are 50 posts in that thread, but for one reason or another (I didn't look closely), not all 50 posts are visible. This happens from time to time - sometimes blocked spam or posts that are automatically flagged that need to be moderated, etc. These are usually, though not always, spam posts that the software "thinks" is spam - and leaves a place holder waiting for a moderator to "okay" the post (else delete the post.) There are a couple of other things that can be causing it as well. Usually, the page thing isn't an issue, unless they linger for quite a while right at 50 or however many posts depending on the number of posts per page that you're viewing. It appears that if that thread gains 2 more posts, the issue will automatically resolve itself.
