I just finished reading the article 60 Years Ago Today: The Day A Meteorite Hit Ann Hodges (Bad Astronomy blog, Phil Plait) and I couldn't help wondering what the medical term for the fear of this would be...
There is meteorophobia for fear of meteors or meteorites. But it obviously covers the fear of being hit by a meteorite also.
This fear may have sprung from news or articles describing meteors that have struck households and businesses. To obsess about the possibility of being hit can lead to phobias. Anyone who has lived around someone with this fear can possess a reluctant, but growing acceptance of the same fear.
But this person can be called neurotic also because it is an extremely rare event to worry about.