Anatomy scan

So I had a very detailed ultrasound a week ago and everything looked good except the doctor found a very small "soft sign" on my baby's heart. It won't get any bigger or anything like that but it is considered a soft sign for a chromosomal defect. All the other signs for certain defects were not there but sometimes babies have little things that can be an indicator for these defects. The doctors told me not to worry. Like any mother I do have a level of anxiety...I'm not interested in an amniocentesis so I'm going to get the non invasive prenatal blood test. If it comes back negative then, I'll breathe a little easier. Has anyone else ever experienced any "soft signs" or heard of them?