No, it has come up. It happened to me several times after the switch to Discourse, which is why I started to look into the issue and why I brought it up several years ago.
It is has continued to happen with enough regularity in the last three years that I still think it’s worth addressing.
Edit:
Maybe not a notification then? How about bumping the original locked thread so that it shows up at the top of a user’s Unread page?