To my knowledge, the standard, production line acoustics get the same necks (barring wood differences like the maple neck on the 6xx series), so your neck might have ended up on another series. The T5 and slim carve necks are available on any model, but are BTO options, not standard on the acoustics.
Note that, grading wood is about aesthetics, and mahogany is pretty consistent from piece to piece, so I doubt there are different grades unless it's a particularly figured piece of mahogany needed to match a presentation series' or BTO's back and sides. And, unlike figured sapele, figured mahogany is not all that common, so I suspect that even this is pretty rare.