I believe there are a number of 'odd' things with 'moved' posts. The one I find really frustrating is when an 'unread' post is moved to a new board, but maintains its 'unread' status in both.
There is a similar issue at Forum level where both the 'Last Topic' and 'Last post' per board seem to remain 'highlit' as 'unread' despite having recently visited the board and read all of the outstanding posts. Compand this with the unreliable post count and it makes keeping up with new entries take more effort than it needs.
Unlikely to be fixed though given the current level of support activity.