Probably just a minor processing error in your sound driver and nothing to worry about. I think I have had a similar experience with a particular white noise machine with hearing some slightly patterned sound when there wasn’t really a pattern. If it’s bothering you or increasing can’t hurt to go see a doctor (well can’t hurt too bad as long as you’re insured…) and get their input.
How can any line that is on the surface of a sphere be straight rather than a curve?