atlrus - 1:32 pm on Sep 1, 2012 (gmt 0)
I have seen this for about a month now.
Sometimes there are only 7 results returned on the first page, but when I hit "refresh" - they become 13. If I don't refresh the page, the second page of the results starts from #11, effectively not showing results 8, 9 and 10 at all.
Not really sure what's the point of this, but it appears that if your website ranks #8, #9 or #10 - it won't show sometimes at all for that particular search.