I would definitely address it sooner rather than later. Otherwise, you'll just keep thinking about it and making it worse. If your T is open to emails, certainly send one...but sometimes, stuff like this is better addressed in a phone call, so that you can give immediate feedback and there's no room for misinterpreting the words. If you feel more comfortable with email, maybe you could email your T, tell her what's bothering you, and then ask her to give you a phone call to discuss it.