Just looking at my forum stats and I noticed that the page views for the 1st April are 489, but the page views for April are 486. Surely they should be the same.
Did you try to refresh the page? I'd say that's only caused by delay, and / or the fact that the numbers were loaded at a slightly different time.
And it could be caused by the cache too.
Seems it could have been caused by either of those mentioned. When I refresh the page the two figures tally up :)