My three-year-old son recently watched Monster's Inc. He enjoyed the movie and laughed at the funny parts but there has been a side-effect of the plot. He's now afraid of doors at night time. He sleeps in our bedroom. Our closet doors are sliding and he doesn't seem bothered by those, however, he is bothered by the main door. He eyeballs the door frequently as he is going to sleep and is uncomfortable if my wife or I are not around. Previously he was perfectly fine by himself and would fall asleep within minutes of his head hitting the pillow.
How can we assist him in getting over this fear of doors or is this just a phase we're going to have to ride out?