Hi had this exact issue with kass when I brought her home in February (and posted about it on the GRA board). I took down the wall mirrors in my room (where her bed was initially) and closed the doors to our bathrooms and other rooms. She would look at herself in the reflection in the fridge sometimes and in reflections in cars. She seemed to really believe it was another dog, and used it as her "safety". After about a month, she's settled in a bit more and wants to be with people, I've put the mirrors back up. She was interested when she saw her reflections again, and wags her tail still, but isn't obsessive about it.
So, I guess what I'm saying is I'd limit her exposure to the mirrors for a bit.. until she can trust her new environment a little more.. then slowly start re-introducing them. She'll realize that it's not another do soon enough and tire of them!