My teacher wrote it, and she is indeed a native Japanese speaker.
I felt that it was weird when I first read it, but I didn't want to go questioning my teacher right away. Her English can be a little shaky, anyway, so it's frequently difficult to get the answers I'm looking for.
Also, I now have two sources of conflicting information, one being a confirmed native speaker, and the other being you. I hope you don't mind me asking, but what is your source and/or what makes your answer credible? I don't mean to sound rude, but you pretty much said my teacher was wrong, so it makes me wonder what background you have that enables such a confident statement.