Is my gerbil going to die?

i bought two gerbils today (two sisters, roxy and quicksilver) and they settled into their new home fine, but i just got back from town after a night out and roxy was sitting still with her eyes closed, i reached into the cage and gave her a stroke to see if dhe would react, she was still warm, so i picked her up and she squeaked and i put her back in and she returned to normal. but after about half an hour she is returning to the same kind of mood. what should i do? they are both 8 weeks old. does she maybe miss her other sisters?