Shirley Yamauchi told Hawaii News Now that she was headed to a teachers' conference in Boston last week and took her son along, paying nearly $1,000 for his ticket.
Things went smoothly on the first leg of the trip from Hawaii to Houston. But as they awaited takeoff to Boston, a passenger who had been on standby approached her, saying her son was in his seat.
Yamauchi said she alerted a flight attendant about the issue, but the woman just shrugged and said it was a full flight.