i had quite a long email discussion about that with Nick Yap.
(started here http://www.casinoaffiliateprograms.com/bb/showthread.php?t=23439&page=2 )
is not solved/fixed yet
i also send screenshots about that
does not seem to affect the “proper” stats
it only happens during our west european “morningtime”, later on the day this discrepancy dissapears