No, it's nothing to do with the last post column. It's still in the actual forum itslef AS WELL as being in the new location (the subforum). When you click on the topic in the forum, it DOES take you to the same topic in the subforum, so it looks like it has moved BUT it still appears to be in the old location (the forum). It's not a marker either, it's a "real" looking topic entry.

No JM, they weren't stickied.

I want to delete the orig in the forum BUT I have a feeling that that would delete the subforum one as well:-(