A Bad Case of Nostalgia

I know it's serious when even even the closing for MASH, which I disliked when I was growing up because it was boring (I didn't understand the humor), causes a flash of sadness now. So what is the psychologicla explanation for this? A consequence of my growing up with the TV as a friend instead of socializing with others? I did have friends at school, but I never saw or played with them outside of school. I don't remember many other children on the block. The TV shows provided familiarity, comfort, and the virtual presence of other people? I wonder if I am alone in this or if it is a common psychological condition.