I don't know if it's a bug or just my being newbie with Drupal, so let me categorize as a support request.
I was importing a big mailing list with thousands of messages when I noticed this. During the process when a forum topic was created, the "Last post" column was set to the actual date/time of importing while it showed the right creation date/time in the topic column. If such a post has no comments later, it's positioned so forever. But if it has at least one comment later, then the "Last post" column changes to the right date/time of creating the (last) comment, which is the expected behavior.
To put it in other words. With a node only, the "Last post" shows when it was imported, but later changes to the comment(s) creation date/time, If one arrives at least. I suspect it's a bug but can't say for sure as I'm far from knowing every bit of Drupal yet, maybe it's just my ignorance. Btw. I had the same experience with AF 6.x-2.0-beta1.
Can someone take a look at this issue? Thank you for your help.