We are seeing things as recently as this morning. If you are looking at "new posts" you will see all posts that people have replied to. Many times, someone finds a thread started several years ago and replies that that. So while their portion is new, the original is older. That's the great thing about the DavidCo Forums--you can tap into years of history and group wisdom here.
But if it's a bug you're talking about, we'd want to know about that.
I figured out that my "Display Options" (down below the posts) occasionally change to show only the last [short period] like the last day or whatever. I just change the drop-down to a longer period and voila... they are back.