I have a Janome6500 for over 4 yrs now and it has never done this, gratefully.
What it does do, irritatingly, ... the needle/foot lever sometimes wont' stay up it keeps cluncking down when I want to lift it. grrrrrr. now I have heard that is a common problem with some Janomes. I'll mention it next time I take it for servicing.
warm quilt hugs, sue in CA