Older folks seem to have a thing for this, especially overly happy aunts when visiting on the holidays. Did your older relatives ever do this to you when arriving when you were a kid?
my older relatives i've only met once or twice in my life, and only those on my mothers side at that. and that was a long time ago. and most of them are very probably dead. considering i'm of an age to be an older relative myself. and have not the slightest interest in pinching anyone's cheeks.