My 19 year old is very affectionate and does all of these things too. There is a slightly jokey, slightly ironic aspect of it, but it is also sincere at the same time. It is lovely, and I feel so lucky that he is like this.
He has always been physically affectionate, and has never been embarrassed by me or his dad.
He is very independent, has had two serious long term girlfriends, is going abroad to university next year, worked very hard in school, and is working very hard and very independently in his gap year. He is lovely, and your son is too, OP.
People in our culture are uncomfortable with men being physically affectionate, and are constantly confusing love with sex. Only little boys are "allowed" to hug and kiss in a non-sexual way, and once they are in their teens, they are supposed to be almost no contact (unless with a sexual partner or in a rugby game). Maybe this is one reason we have so many problems with sexual abuse: men are brought up to think any sort of physical affection is somehow either babyish or sexual, which is completely wrong, and very sad.