Could a WBC count o f 22,000 cells/uL indicate leukemia?

My 1 year old daughter went in for her 12 month physical and they drew blood. She had no fever, runny nose, UTI, etc. She was happy and healthy. Her white blood cell count came back to be 22,000cells/microliter. The doctor wants to retest her in a month to rule out infection. Is 22,000 a high enough number to worry about the possibility of leukemia?