Posts are added to the post count whether or not they have been viewed by an admin.
If your system is there to discourage someone from signing up and spamming the forums, this is a rather major loophole, as all you need is 5 posts, then spam away. If you wanted to be especially devious you could make 5 normal looking posts then spam to your hearts content until someone reported you.
Or if some other odd reason like to weed out the initial posters so they dont act like tards, this again is an issue and a very possible loophole.
I looked over the first pageof this forum for posts like this, however didnt search on it because even if it has been mentioned prior IMHO this is important enough that it bears reminding(well and i suck at searching and i have no clue as what id search about for this one).