KG expressed some frustration last night about having to play center, but the fact that he signed back with Boston was probably the only indicator you needed that he is fine with doing it all over again.
That position really revitalized him in some ways, suddenly he gave the Celtics some interesting options as he was quicker that the opposing five and could help stretch the floor with his outside shot.
The Celtics added some big men in the off season this year, such as Chris Wilcox, Darko Milicic and Jason Collins. This had some speculating that perhaps KG would return to the 4. Doc squashes those rumors here.