This is just a guess on my part, but I've heard that Kubota might be doing a soft intro on that model. Waiting to see how the market will respond to this model before making a SPLASH!
It's been my experience that the tractor manufacturers are rarely speedy to put up new products on their sites. Deere's site, for example, just put their new 4x10 series up very recently, while the tractors have been out for a while now, and midlawns.com (a dealer site) has had pics/specs/prices up for a while as well. So I would guess that they're just plain slow.