The reason I doubt it's simply sales is the fact that supplies to the stores have been so constrained. This has never happened before. I also don't believe the story about this is an attempt to drive sales online because units are slowly trickling into the stores. It's got to a constrained component driving all this. Everything else is just behavior that happens in trying to deal with this.
I think it is Apple's new way of selling products. I think they want to have people order online.