Nerves. If she is 6 and you have only had her for 24 hrs she is scared. Her world has been turned upside-down. I don't know the situation she came from but bullies tend to be OCD and take time to adapt to change. Panting with a big change isn't abnormal at all. Give her a few days settle in to the new surroundings and routine. Give her all the love you can in this time as well to reassure her that everything is ok and plenty of water to boot.