Well, I must say... even though your mom to him your still a women, with a womens body, even a hug can make a 13 yr old react with his body, Mom as cute as it was when he was 2 1/2 he is growing into a young mans body with a young mans sexual needs. I Know I Know ... ewwwwwww I am mom OMG !! yea I said the same thing, although I caught my son asking to see who is taller me or him, back to back, he was getting a butt thrill... gross, being we had a talk with him, he never did that to me again although I have caught him doing it with others, the doctor told me it was natural, ( yea sure doc )
as long as it was mutual.. he has his own bed thats where he should sleep, unless he is sick and you need to stay next to him, I am sure there are other reasons, but to snuggle in moms bed. Not a good idea.
Good Luck all part of growing up