Sure. Enjoy him while he's little. He'll be sassing you and complaining about how boring it is at Granny's in no time.
I was crawling around the floor with mine last Sunday evening. He's not really walking yet. We had him overnight last week, his mother was in hospital delivering his baby sister, Daddy was helping her so Nan and Grumpy looked after Zach. Major case of deja vu - that child is a dead spit for his father at the same age.
He lives with us. My son, me and my sons son. He has since he was born. Im enjoying his littleness while I can, because you are right, one day he will be old enough to not believe my lies.