I'm not sure, in all honesty. I just responded twice on that page, once as a 'new' comment, the other as a reply to the existing one. I then logged out of Facebook and could see both the posts. I also could see them with a different Facebook user logged in. Can you see them? Also, feel free to delete them.
The new Comments functionality introduced by Facebook in early March, which we now use (it will be required at the end of April) does have threaded comments. They say this is much better, and we'll have to agree because they give no choice to disable. They do mention in their post a few other things to consider:
* Comments marked (or automatically detected) as spam won't be shown
* Comments will show in the order of relevance to the user - which means you'll see your friends' comments first, not necessarily the newest or oldest first.
* Within a fork of comments, my understanding is that all comments will be chronological though, so there will be some order to them to follow the thought process of the comments
For more information on the update, see:
developers.facebook.com/blog/post/472
Also, let us know if you can see the new posts that we made. You may also want to check the Comment Moderation Tool to see if your comments are showing up there. Sometimes, it can take a while to appear there though:
developers.facebook.com/tools/comments/
Good luck!