I agree, and wonder if the pup is in a new temperature region? Stress from leaving siblings, the familiar environment can take its toll, I wouldn't change the diet so soon. Heat or warmer temps make some dogs go off food some, too...
Call your breeder and let them know she's not eating much, was she picky with them as well? Most pups are ravenous, due to the competition with littermates.
Hopefully she'll settle in and her appetite will kick in. Picky eaters are a pain, and training a pup with low food drive is even harder.