LinuxQuestions.org - Some posts remain marked unread and have mismatched time stamps

Something is wrong and I don't know what nor whether it can be fixed. But let me describe what I see ...

The majority of threads get correctly marked as read when you read them. So, as long as there are no new posts,

they stop showing in bold in the ucp http://www.linuxquestions.org/questions/usercp.php and in the various new posts views e.g. http://www.linuxquestions.org/questi...ew&daysprune=7
if there are new posts since you last read the thread the "go to first new post" button appears and correctly goes to the first new, unread post

I tend to rely on these features.

But some threads seem to get stuck (until you log off and mark all threads as read, or mark all threads in the given forum as read). They stay in bold and the "new post" button remains there - and always seems to take you to the first post in the thread.

What I've noticed - I'm not sure if it applies to all - is that these threads display a different (more recent) time in the list of threads than they do in the thread view. For example:
gedit save dialog defaults to 'Recently Used' is one of these stuck threads, for me. In the thread list it shows Last post: Today 08:44 but the post itself shows as Yesterday, 16:00 with no evidence of an edit.
HOWTO setup different system language and keyboard layout? also is 'stuck' and has a timestamp mismatch.

Some threads where the last post has been edited also seem to get stuck.

I wonder if this indicates something that the experts at vbulletin.com could use to identify the issue?

---------- Post added 2011-10-23 at 12:54 ----------

As a test - I'm going to edit this post.

Edit: to see if it gets stuck.