Baby grabs face while falling asleep

I have to rock my son to sleep and everytime he’s trying to fall asleep or is almost asleep he loves to grab my face or lips and just rip at it. He always grabs my lips or tries to put his hands in my mouth. My face is bright red by the time he falls asleep because how much he pinches it and pulls at it. Does anyone else’s baby do this and what does this mean??