Referred for first trimester screening...

Has anyone else had their doctor refer them for genetic testing? I had my first ultrasound last week and everything looked great... No one mentioned any issues, but then the doctor referred me for a first trimester screening. I had asked a nurse about at my 8 week appointment to do paperwork, but I'm not sure if that's why they referred me to the geneticist.

I'm in the process of looking for a new doctor because mine insists that all overweight women have a mandatory c-section and I don't think it's medically necessary. I'm not sure if he referred me to other tests because she had issues with overweight women, or because I expressed interested to a nurse a few weeks ago.

Should I be nervous?