The US site alternates between two different promotions, the iPad Mini and the iPad with Retina Display. Every other language's site (I've tried quite a few) which promotes the iPad Mini is showing just a single promotion and exhibits the resize behaviour.
Yep. Here's an example from the Japan site, where you can see the repositioning of the iPad Mini graphic when the browser window is made larger. The UK site has the same behaviour. I don't think there's anything dodgy going on.