This is making me worried. When i was a student at mit, we had trips to boeing facilities in seattle. One time, i was again selected randomly for explosive trace sample collection from hands. I dont know what it was, but when they put the tissue in the machine, the machine showed a blinking text saying explosive detected. The tsa agent(iirc) paniced, tried to call out his supervisor while trying to keep an eye on me.

Now usa probably has more experience with false positives, i am curious how i will be treated when i go visit my parent :)