The views are based on a 24 hour period... for example from 10am the previous day to 10am today. So as the day progresses the 24 hour period shifts. It's not an exact real time and doesn't add together throughout the day. So if your views have dipped during the day its because sometime in that 24 hour period you had less views than the previous 24 hour period.
I believe there is something in the learning center regarding how they do views. If you want real time views, use Google Analytics.