Hm, cleaning up the rules (again) does seems to have resolved the pop up issue. For now, that is. To be absolutely sure I still need to wait and see if it will start popping up again later. The notification is still there though, every time Chrome is started. Even without using any website or service that makes use of the web camera, but then again that's Google's logic I guess
BTW, attached image, what my webcam rule list used to look like before I cleaned it up. Fingers crossed that it doesn't repeat like that again.
Thanks!