That line separates the description section from the rest of the survey. Did you make any other changes other than the group name? I would expect it to be below your instructions. I only changed your beginning group name and published your XLS and see what I expected.
If I change the generated_note_form_title to a normal note, then I see what you are seeing.
There's no real way to control that line. You can hide the entire description section (and line) using a URL parameter ?hide=description. If you do that, then you would need to ensure your instructions are not in the description area.
Alternatively, you can move your instructions back into the description area to make the line make more sense.
- Jen