Date change to July 15?

Tue Apr 28 22:31:34 UTC 2009

So, what's up with this, does anyone know?  All of a "sudden" [sudden to me, though it might have been awhile ago], the release date at IMDb and at Warner's HBP page is listed as July 15 instead of July 17.

Don't get me wrong, I'm thrilled for many reasons, but I wondered if anyone had seen discussion of this at Leaky or elsewhere which gave an explanation?  And are we SURE?

Siriusly Snapey Susan, who's got a long day of travel on July 17, so she's really hoping July 15 is right