Mine too. I got the starlight 41mm and started hearing the sound when I was at home on the second night while charging it. It got pretty audible and noticeable—I went back to the store and they did an exchange for me. The same thing still happened and I could still hear the sound.
This time, I went back and got an exchange for the pink 41mm. Let’s see how it goes—I hope the sound doesn’t come up again. I’ve also never had this issue with my series 6—the charging was quiet as a mouse—so I was pretty concerned over this as well.
I hope it’s not a batch issue—I’ve been trying to google to see if anyone else experienced this but your thread is the only one I found! Hopefully if anyone else also experiences this we can find out more. For now I’m just wondering if I’m too sensitive to sounds—which I actually am.