Does the thought of someone smoking annoy people?

Ok, just got given out to by a housemate for smoking in my room, even though my room is on its own at the end of a corridor so she had to go out of her way to use the bathroom beside it. She left this bitchy note saying 'FYI its a no smoking house.. take your cancer sticks outside,' though there is nothing in the lease to that effect. I'd never smoke in the company of someone who doesnt..but why would the thought of me smoking in my own room annoy somebody so much!