[scoussysows]

I don't think you did anything wrong -- why do you think you did something wrong? Because they turned their heads when your ball landed? I've heard balls hit behind me, with no danger of hitting me (or even rolling to me), and I instinctively turn my head, maybe even look back, but it doesn't bother me as long as it's a rare occurrance. I know I'm sharing the course.

You did nothing wrong.