In a new house six months and I have some doors that have pulled away from their frames which I believe is normal and they can be rehung - however one door has contracted greater than a half inch and door latch no longer catches!! So the door swings in the breeze!
If its that much off I would go back to the contractor about it as that is definitely not normal. There is always a certain level of expansion & shrinkage in doors of new houses due to the initial high moisture content.
Is there a possibility that the door was planed down at an earlier date?
A good chippie could probably offer better advice but I would think that a larger door stop can be fitted. Thats the piece of wood thats nailed to the frame against which the door closes.
Its called a door stop or stopper because it basically stops the door from moving any further after you close it.
I would still be concerned at the extent of the gap that is there now. That would not be normal and I would still suggest that you bring it to the contractors attention