Especially when your only child has your first grandchild!
Course, their daughter got pregnant by a foreign man, before she was married. In 1961 this was still cause for embarrassment. When my sister had a child out of wedlock in 1978, my parents were horrified and humiliated. So, perhaps they were estranged, at the time?
I am pretty sure they got over it, and Obama said that his grandmother loved him more than anyone could love a child.
According to reports, Stanley Ann Dunham was not known for her admiration of the institution of marriage. I’m thinking the parents were probably not so surprised by this turn of events.
It seems that her parents did not have any hesitation to take Obama into their home and raise him when his mother sent him back to Hawaii. I suppose it is possible they were estranged ten years earlier when he was born.
But first grandchild, as you point out, of their only child? Hard to imagine.