Well, back to premonitions.. as to why they happen, I have a theory. Obviously you weren't given time to do anything about what you saw. It really has only served to show you that there is more to reality than you would think there was if you just watched tv or read the newspaper.
But the fact you get them probably means you have some as yet undeveloped psychic ability. If you wanted to, you might try to develop this. You might get lucky and become the Australian John Edwards, or what have you..
But I am not sure I would advise this, now that I think of it. My own experiences with divination has led me to question whether we are really "meant to know" such things..
If I were you, I'd follow my intuition. I have a feeling our hunches can be trusted, if not always our thoughts and plans..