Hello Melissa! I ran some tests from my end, but I don't see any section lines in my Rise course.
I am getting a line below my video block IF a caption is added (or even just spaces). See this short video recording (no audio) for reference.
Is this what you are referring to? If not, would you mind sharing the entire page or the steps to replicate this behavior so that we can properly test it from our end? If you don't mind sharing your Rise 360 course with us, you may open a case here to get in touch with our support engineers.