The 1 day, 7 day, and 30 day page view columns are continuously updated totals. If your 1 day total shows five page views, and one of them was 23 hours and 59 minutes ago, the total will drop to four page views when you check back a few minutes later - unless someone else looks at your page.
The page views column labeled 'ever' is a cumulative total, and should never go down. If that is decreasing, then something is probably wrong and you should check with the HubPages staff. Good luck!