Calling my SO the teacher Mr....

So my SO is a science teacher for middle school and high school. I think it's one of the sexiest things about him (intelligence is so sexy). So do you think it would be incredibly weird if when we're getting kinda dirty that I call him Mr. (I'm not gonna put his last name here) instead of using his name? I don't want it to weird him out. I plan on talking about it with him but I just wanted to see what you ladies thought. And no, I don't have teacher fantasies or issues or anything like that. The only teacher fantasy I have is about him. I'm a grown woman, not a student. I'm worried he'll think it's weird that I'd find that sexy because he may find it to be a turn off.