This must be because of all the states getting legal weed, even Colorado getting recreational use, so those states that still have it illegal. Right now the swab is in cali, LA to be exact, but don’t think this won’t spread, so listen to the advice to try and get ahead of it.
Now this could be what make it a federal issue enough to make weed use a federal ‘ok’, hopefully. But until then, prob best to not be smoking in the car, because the smell is what prompts the swab to come out.