Arm around the neck?

So there is this guy who I’m friends with. We had casual sex one night but before and ever since that when he sees me always keeps his around my neck sometimes having his hand loop around right by my chin. Other times his hand just casual hangs down. I’ve really never had a guy do that and I’m just surprised by the physicality of it since we are just friends. What’s the deal?
Arm around the neck?
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