Autos do not necessarily grow faster than photoperiod plant, it all depends on the genetics of each and every seed, be it auto or photoperiod.
Just be thankful you have a real performer.
It could well be one of those "special" plants that all breeders hope to get and it may be wise to take some cuttings from this plant later on, you could have a real "winner" in your tent. Even if it cycles one week quicker than other plants of the same strain, that is one week less electricity bill!
Congratulations on growing a normal photoperiod plant and not another auto genetic freak!
Hope this helps,............
Organoman.
(and signed up member of the "Anti Auto Party" or the AAP!)