There are a few reasons, namely that:
It came right after the fifth anniversary, so a lot of the look-back stuff had just been done.
The number didn't reach 4,000 till late in the news cycle for East Coast and Midwest papers, and it was aSunday night.
It's something of an arbitrary number, which was exacerbated by the above two reasons.

Why would Mr. Tackett make such a comment without checking first? Is the need to blog these days overwhelming the need to check for truth? Is this what we are swapping out newspaper-based commentary for — a lessening of veracity for a punchy comment? This news moved at the very end of the news cycle. However, we (Fort Myers News-Press) recognized the importance of it and at least got it on A2 for a late edition and then did more with it the next day. We're one of those "dozens of smaller papers" but we still understand and cover the "news." Mr. Tackett, when newspapers everywhere are trying to figure out how to survive in a world of blogs, Web sites, Flickr, YouTube et al, please don't cut us short by falsely saying few of us covered such important news.

Let me add, we also got it a top of A1 promo skybox for the final edition, we had the story inside for ALL our editions. Took a while to get the color change scheduled.