It sounds like you must be making progress if your T decided it was alright to give you a hug. I say enjoy it! I wish my T would give me even a little hug, but it will never happen. So maybe now your T will hug you more often. Others have written here that it can be really healing, and a few have said it's the best part of the session!

If it bothers you, you could bring up the subject and say what you said here, that you were really surprised. Might lead to a good discussion that would make you feel better about it.