Is unintentional jhana possible or even common?

I have a friend who is a Christian. It is a truism that most people can't tolerate sitting and doing nothing because of catastrophic dukkha. Most people, including people I know, have to DO something all the time. But my old friend would spend hours sitting on his porch, a smile on his face, by himself, just enjoying the present moment. Is this a form of jhana? Is it possible that there are many run of the mill, non-buddhist people who actually understand and practice a kind of jhana unintentionally?