It is likely a bug, some cache needs updating somewhere. I had similar issue with Twitter. I used some sort of extension to delete my old tweets. It removed all

It is likely a bug, some cache needs updating somewhere. I had similar issue with Twitter. I used some sort of extension to delete my old tweets. It removed all of the tweets but tweets count didn't change. I am sure count is cached somewhere and when a job or some event triggers update, it will go down.