I would get really iritated by that. Especially if you've seen the T for over a year. Is your last name difficult? I've had teachers who after months till had trouble with some students names. My name isn't difficult. And T doesn't use my last name much with me. But if for any reason she use my last name, I expect her to use it right. If she wouldn't be sure, then I expect her too look in my file for how to write it.

So if you're really bothered by this, jus say it to him. Though that can be hard. I sometimes find it hard to correct my T or pdoc and then I just don't say anything.