There's no need to get worried. Unless Anton for some reason suddenly changes come on and changes it, then I dunno. But that's usually how the game stores work. They get the pre-orders first, then file them all away, and then get the mass shipment of the non pre-ordered. And they are all released on the exact same release day
Pre-order shipment= Sep. 8th (Gamestop and others)
Release= Sept. 15th
And thank you, xNikex