Hi imajenarry,
Do you mean your friend has a regular blood check, or gives blood? Your first sentance reads 'my friend has blood regularly'.....
The very fact that they have called her back for a further test means they are keeping a check on her, so don't start worrying unduly until they give her the results. When younger I suffered from anaemia, and my white cells outnumbered the red due to my condition, so it might be this.
Try not to worry too much, as you can only wait and see the results before trying to guess (and getting it wrong) as to the cause.
n00dles