Over thinking ?

I went to the doctors on the 25th for my 20 week anatomy scan and they checked everything and baby looked all good! I get mail today and included was a approval letter from my insurance company that I assume was for my last scan since it was dated the 17th. It said for an ultrasound and that the diagnosis code was for high risk pregnancy?! I'm not aware of being high risk and when I called about all my results for blood work all was good. Did my OBGYN put that so I could get extra measurements during the scan and check everything out? I can't call till Monday to find out and I'm freaking out. I would think that she would tell me if I'm high risk or not.