OK, arguably I don't care much about post counts, which is why the timespan from me noticing this to reporting it has been a few weeks.

It seems my post count has been stuck at 572 for some time. Can't tell you when it started... can't count my real posts since the "posts by user" only go back 500. But I'm sure it's a lot higher than 572.

Edit:
I just posted this message and it incremented to 573. That implies that posts in certain forums don't count. Is this a correct assumption?