$node->comment_count is broken

$node->comment_count is returning the value of 1 in a blog post that has no comments. It returns 1 in two of my posts, both of which are the first one listed on the page. That is, there are two pages of blog teasers, and the first one on each page says "1 comment" even though one of those two posts has a comment and the other does not.

This happens regardless of whether or not I use the views module to display the teasers.

I'm printing $node->comment_count in my node-blog-teaser.tpl.php file.

I'm using CCK 6.x-2.1. The same problem existed in CCK 6.x-2.0.

I just tried adding a test comment to a third post -- one that is not currently the first one on any page -- and doing so didn't affect the other comment counts. In other words, after adding a comment to a third post, I see "1 comment" on three of my posts, two of which have a comment and one of which does not.

This is the relevant code in my node-blog-teaster.tpl.php:

<div style="clear:both;"><ul class="links inline"><li class="blog_usernames_blog first"><a href="<?php print $node->links['blog_usernames_blog']['href'] ?>" title="<?php print $node->links['blog_usernames_blog']['attributes']['title'] ?>"><?php print $node->links['blog_usernames_blog']['title'] ?></a></li>
<?php if ($node->comment_count > 0) { ?><li><a href="/node/<?php print $node->nid ?>#comment-1"><?php print $node->comment_count ?> comment<?php if ($node->comment_count > 1) { ?>s<?php } ?></a></li><?php } ?>
<li class="comment_add"><a href="/node/<?php print $node->nid ?>#comment-form" title="Add a new comment to this page.">Add new comment</a></li>
<li class="node_read_more last"><a href="/node/<?php print $node->nid ?>" title="<?php print $node->links['node_read_more']['attributes']['title'] ?>">Read more &raquo;</a></li>
</ul></div>