Why?

This is one of my riddles, I can't say it's great quality, since my English isn't that good and i have translated it from Dutch.
One tip: Leave you're emotions aside


John is a full-time nightguard at Brother. INC. where he has been working for a couple of months. As the enthusiastic man he is, he is well-liked by all his co-workers.

One friday though, he makes an appointment with his boss, Mister o'connel:
"Well hello John! Come in! What can I do for you? Do you want something to drink?"
"No, thank you Sir."
"A nice cigar then?"
"No, thank you Sir."
"You aren't overdue for a promotion are you?"
"No Sir, but thanks anyway."
"What do you want talk to me about then?"
"Well Sir, Last night I had a dream."
"Yes?"
"I dreamt that you were getting inro an aircraft with the departure number 214587, heading to hawaii. I also saw your wife and children there. You got into the plane and it lift off, soaring into the sky. But once over the Atlantic, one of the engines started to fail and the whole plane crashed into the sea, leaving no survivors."
"That's strange, I'm going to hawaii tomorrow;AND I'm taking my wife and children; AND the departure number is 214587"
"Sir?"
"Well, I'll think about what you said John, until next time."
"Goodbye Sir"

Sunday morning, John picks up the paper at his local bakery and reads the headline:
"SABENA-plane crashes in the Atlantic!"

The next day, he's called to Mister O'Connel:
"Hello Sir!"
"Hello John."
"Can I have a drink?"
"No John."
"A drink then?"
"No John."
"What about that promotion? I think security manager would be alright.
"
"No John, you're fired"


WHY?