Over the past few days, the API has been reporting 0 pages for my sites very often. Usually it only happens about 10% of the time, but lately it has been closer to 60-70%. If this happens when the Coop revalidates you, your weight goes to 0 but you don't get an email (because technically, your site is still validated). If you don't do so regularly, I recommend logging in and checking your weight - just to make sure.