Trotter was scheduled to leave from Denver at around 11 a.m. Monday. However, when last-minute seats were available for an 8 a.m. flight, he rushed to make it.
As he and another passenger waited at the top of the ramp to board, he saw a middle-aged man in a button-down shirt and jeans running off of the plane.
"All of a sudden this guy pushed open the gate from the other side," Trotter told BuzzFeed News. "A gate attendant said, 'Sir,' repeatedly but he didn't respond. He put his stuff down on a chair. You could tell something was going on."
"He kept shaking his head, staring at the door," Trotter said of the man.
He said employees and others looked on confused and concerned. One gate attendant apparently went to speak with the man and began consoling him and rubbing his back.