False positive for Down syndrome?

Anyone else have experience with the second trimester screening and false positives? I️ had two nipt tests (progenity) come back negative for chromosomal disorders but screening for state come back 1 in 55 chance for Down Syndrome. My doctor isn’t worried because of the ‘accuracy’ of the nipt but I️ can’t help but being nervous. Anyone else get a false positive with the quad screen?! My baby’s NT was normal and all ultrasounds have been great. Still scared! Hoping it’s false positive.