William Stratton had just settled into his seat for a flight from Chicago to Phoenix, US, on the weekend. But this wasn't to be any ordinary trip.
Because shortly after the plane taxied away from the gate, a Frontier Airlines flight attendant approached his seat and handed him a note written on a serviette.
Bemused, he opened it up and found the seat numbers 10F and 13F written at the bottom along with words "other armed passengers".
It turns out the note wasn't meant for him, and the flight attendant had mistaken him for an air marshal. It's standard procedure for air marshals to be notified of other armed passengers on a flight.
Mr Stratton said the situation made him feel uncomfortable, and concerned, while a former air marshal told Fox 10 that had the note been given to someone who had bad intentions, it could have been a catastrophic mistake.
"We were about to pull away from the gate, and the flight attendant said sir, here is the rest of your boarding pass and handed me a white piece of paper," Mr Stratton told Fox 10.
"Well, I didn't really know what to think. I went up to her and said 'ma'am this wasn't intended for me'. And she just said 'oh god', and that was it."
A Frontier Airlines spokesperson said: "The note was handed to another customer instead of the person it was intended for after the customer changed seats on the plane."
However, Mr Stratton says that's not true, as shown by his boarding pass.
"Those are the seats we were assigned; those are the seats we sat in. I can't imagine it's very easy just to change seats, let alone with someone who is assigned a specific seat for safety purposes," he said.