We call it fever when it is above 100°F at any time of the day. Generally a normal human body temperature can rise upto 99°F during early morning or early evening. Then we don't call it fever. So firstly,  you need to track the temperature. Secondly if it stays above 99 or touches 100!° at most of the times of the day, then you need yo go for investigations. Now in your case, cbc is already normal.  May be its just physiological rise of body temperature.  For that you can take plenty of water and moderate to high potassium diet. In case she has any symptoms along with,  she needs to  be examined accordingly. 

Need detailed history and evaluation