Well in your relaxed state your body temperature could of fallen accounting for the cold shoulders. There could of also been a draft in the room. A spirit randomly trying to drag you out of your meditation I've never heard of it but it is possible, not very likely in my opinion though. Possession takes a lot more work thank grabbing someone, you need to be very weak mentally, physically, and spiritually.
Myself I have been bothered by spirits while meditating, but its just Rori [spirit I live with] wanting me to pay attention. He will pace the room, or say things to break my concentration, not attack me.
You could try talking to it, or burn purifying incense in the room when you meditate.