Not enough fetal DNA

So I just had my genetic testing done last week, and I’m still waiting on the results. The nurse called me yesterday to let me know that they were unable to determine the gender because they did not find enough of the baby’s DNA in my blood to get a result. Of course, I have been worried and freaking out since finding this out. She asked me to go in for a redraw next week.

Has this happened to anyone and have they gone on to have a healthy baby?

I was 11 weeks 4 days at the time of the blood draw, however my baby has always measured 4-5 days behind. Which would have put the baby at 11 weeks exactly the day of the draw. The nurse also told me that out of 10 women she does the test to, at least 1 of them gets this same outcome.

Should I be worried? Everything until now has been progressing normally. And the same day I had my blood drawn, we heard the heartbeat!