this is the reason-
Hi folks,
I've been making behind the scenes changes sine we moved to my server a few months ago in order to maintain a high level of performance and reliability. Although the post counts didn't pose any potential problem, I decided to bring everything up to date.
The post counts now represent posts which currently exist rather than all the posts which were pruned over the past few years. I've disabled all "automatic" pruning now so this shouldn't happen at this level again.
Hope this helps,
Andy