A few weeks ago my total post count went from 9 to 4. Over the last few weeks I made a few more posts and my post count was up to 11 when it today it dropped down to 7.
When I look in my profile my last 20 posts show 11 posts instead of the 16 I had made, while my post count shows 7. Nothing that I am going to loose sleep over, just thought I would mention it in case it is a bug.
I did a quick search and could only find this thread dealing with missing posts, which doesn't seem quit fit what I am seeing.