Maybe it'd be good for her to point out that she's doing that, and ask her to think about it? I confess, when I was dating a transman, I told my friends and then thought about it afterwards and was uncomfortable that I'd just done that without checking with him first. It was good for me to think about why I was doing that - and I confess I also didn't have the balls to tell him I had done so (but then it was a long-distance thing, and he wasn't meeting any of my friends, nor I his).
Sure, if you'd just rather she didn't do that, it's fine to tell her so, but it might be more creative to get her to think about why she does that (and for you to explain what about it bothers you, once you've clarified that for yourself!) - a good conversation for both of you to have.
