This question could be asked often in future so before any does, here is a link to a thread that answers the questions: http://www.forum.trshady.com/viewtopic.php?t=12547
Basically if you post in a thread that is removed from the forum, or moved into the 'Backstage' section then the post count will not be changed when it should .. so once a week I run a script that recounts everyones post count to the true amount. So if one week you lose 3 posts or so, just remember this is why and its nothing to worry about.