A writer is...
Watchful -on the lookout for book material
If you think you're being watched, it's probably just a writer gathering information for a book!
Have you ever "watched" people to get information for writing?
I have. I sat in a coffee shop once and took notes about the customers. I dreamed up lives for them based on what they looked like, what they wore, and how they acted. (P.S. It is also very entertaining. I got to see a man dressed in bacon pajamas. His PJ's read "Everything tastes better with bacon".)