This is just a guess, but it could be that the number you first see is the number of previous people who have viewed the page, and that once the system "knows" your browser has loaded the page, it increments the number by one, so that when you hit refresh, it uploads the new number, which now includes your first view. If you hit refresh again, the number no longer increments. At least that's what I saw happen when I played around with a few random pages I hadn't viewed before -- the first refresh made the number go up, but later refreshes did not.
What makes me think the systems waits to increment the number until it "knows" you've viewed the page is that a few times (initially by accident, and then intentionally) I hit refresh before the page had finished loading and saw that the number did not go up by one, but if I hit refresh again after allowing the upload to finish it did go up (but not for any subsequent refreshment).