I have just returned from a journey to Kiev on the train and would be interested to hear your thoughts on the following.

I have never had any problems with travelling by train and never had any fears about using any form of transport but for some reason whilst on the overnight train from Moscow to Kiev I was getting some worrying thoughts in my head when the train started rocking and rattling more than I had ever experienced before. I kept thinking any minute now the train would derail or something. Now I'm just confused as to where these kind of thoughts come from all of a sudden and could this be how phobias develop? It didn't cause me immense terror but it was still not nice. What's your view on this?