When I went through that transition, it felt weird too. Well, moving to the opposite side of the globe and still having office space back home for 2 years was strange, but even after my defense, it was strange to leave the office. Tenured grad students have such a sense of ownership of their departments that it can't be easy to leave, no matter what the circumstances.
But this is good - it's starting the separation in stages, to get you used to it. Kind of like driving the cat around in her car carrier but not taking her to the vet... ;)