I guess it would have to depend on how you relate to your therapist; what your fantasies are, why you are in the group and what place the group plays in your life, etc. I had a session with my therapist once not in our office (she forgot the keys) but in a restaurant and the next session in the office was a bit weird at first, trying to reorient ourselves to the experience of being elsewhere together and now being back in "this" setting.

I would discuss it with your therapist; s/he may have trouble with the containing/holding that therapy provides, since you will be seeing/relating to her out of the box, so-to-speak and putting the genie back in the bottle is a bit tougher?