My mind was wandering today, as it often does, and I was lead into a memory of a short story I first read in high school. "The Secret Life of Walter Mitty" was written by James Thurber in 1939. If you haven't read it, or forgot, here's a link.
Mitty's daydreaming is usually interpreted as him trying to escaping his mundane life. In his fantasies, he's a surgeon, a navy commander, a man on trial... He becomes men in situations far from his 'forgetful-husband self' out for a day of shopping with his wife. His fantasy lives are filled with tension, exactly what writers need to keep a story flowing.
Maybe Mitty wasn't really just escaping, he was plotting. Mitty really wanted to be a writer, so his mind was always thinking of stories, characters, suspense-- he just happened to put himself in the starring role. Nothing so strange about that. In The Lie That Tells a Truth, a book about fiction writing, the author talked about how all stories reveal traits, hopes, and fears about the writer, even if the writer doesn't mean to.
Besides, the mind of the writer can be a very surreal place for the uninitiated. From one moment to the next, a writer could be thinking about the interactions of her characters, thinking-- would they really do that? Why? So much of my writing takes place away from the computer-- I'll be at the grocery store or the gym and suddenly a scene pops into my head, and sometimes I even stop and wait to see it through (and hope that the pens in my purse work this time!).