I think this is a local AHJ rule based on the "Life Safety Code" not the NEC. In my area for single family residential a smoke is required within 10 feet of every bedroom. They will accept them in the bedrooms, but not required. In fact one inspector told me not to put the smoke in the bedroom because he didn't want the smoke on the arc fault and by code it would have to be if in the bedroom.
Re: Smoke Detectors in residential bedrooms#26372 06/09/0310:38 PM06/09/0310:38 PM
zr6000, in california the requirement for smoke detectors in bedrooms originated in the 1991 uniform building code(1992 calif. building code).prior to that time it was to be centrally located in an area giving access to sleeping rooms.