Gracey,
I can't imagine ever feeling so relaxed in T's office. I mean, I feel relaxed and really safe in his big chair, and his voice soothes me, but it seems to me that the nature of the relationship is such that there is at least a little bit of an edge to it. If I was as relaxed with him as I was with my friends, then who needs him?
Anyway, it's just a thought. I think the couch represents a deepening of the relationship....a willingness to let go a little more and let him in a little deeper.