It both freaks me out and gives me great joy when he uses the "John," because I'm just not accustomed to it and I think I might love it a little too much

Oh yes yes! For all that I've read it in zillions of fics, it's one thing to read and another thing to hear him say it. I have to say that it threw me at first, but now every time I think about it, I love it a little more :">