Night-Shift Security

Riddle: There was once a night-shift security worker. His boss said he was going on holiday to China. The boss them said he's going tomorrow. The worker said he had had a dream last night that the boss' plane crashed. The following day, at the airport, the boss was about to board the flight when he thought, What if the dream was true?? He decided to board the next flight just in case did would crash. When he looked out of the plane window, his original plane crashed before his eyes. The following week, the boss was back from his holiday and he said to the worker, "Thank you for saving my life, however you're fired!!!" Why was the night-shift security guard fired?