Nima is extremely accurate and detects gluten in samples of food at 20ppm and higher with a high level of sensitivity so you should take a gluten-found seriously.
Nima may detect unintentional cross-contamination or cross-contact on an othewise gluten-free item. Talk to your kitchen staff and servers and do your own Nima testing to see if you can determine a contamination point.
Nima can also sometimes detect gluten below 20ppm. In those cases, while the food being tested may meet the standards for gluten-free labeling as defined by the FDA, there may still be some gluten in the item (say 17ppm, below the FDA limit). We recommend doing several tests of the raw ingredients and contact suppliers to ask more questions regarding their validation practices where appropriate.
In many cases, most people avoiding gluten will want to avoid even trace amounts, so from time to time customers may decide to avoid eating the item even if you believe it to be under 20 parts per million.