I am not sure is anyone has come across any behaviours like this but I thought I would ask anyhow

My DS many times throughout the day will in a state of excitement come over to me (could be I just walked in the room, or I talked to him playfully etc) and just before he reaches me he will start clenching his teeth (gritting) then pinch my neck or roll the skin over my collarbone while pinching and then headbutt (or just knock his head on my arm or thigh etc). This seems to be happening more and more often...
Has anyone been through this at all? Is there a reason he is doing this? Is it affection (he only does it to me and my MIL and we are his 2 "favourite" people....he does not do it to my hubby or my other son)...or is this a sensory/overstimulation thing?
Any input would be most appreciated

BTW, my son is almost 2
It sounds like a form of connecting. When I was 13 months, I started slapping people in the face and laughing. It was playful in nature. Something similar could be going on here.