Is it strange to email a teacher?

I just graduated and didn't have a chance to say goodbye to my favorite teacher. I had her class for three consecutive years and was in her homeroom for two of them. She is a really sweet women who I am truly going to miss. We have all the teachers' work emails so we can contact them if we have issues with assignments. I kind of want to email her a thank you for all the kindness she showed me and help she gave over the past three years. do you think this is inappropriate?