Bumped from behind -- how bad is this fender damage?

[Two2Three]

I was leading a group and when leaving a stop sign, they person behind me thought I was "going" when in fact I was moving forward to try to get a view of oncoming traffic.

BONK.

They bumped into me at super low speed and hit dead center in the rear fender. From what I can tell (and I can't find any good info in the service manual) it just broke the plastic fender loose. Seems like it would be called a fender skirt or something, but I guess it's the actual fender. So now it sits almost on the rear tire. It was ok while moving because the air pressure keeps it away from the tire, but something is obviously loose.

Does anyone know what is actually wrong? I can see what looks like what might be a spot where a pin pokes through from the hard plastic tail piece through the fender, but then it also looks like there should be a series of tabs or something holding it on. I can't feel anything or get it to "re-seat" by pushing it in any direction.

I'm going to try to get into a service dept today or tomorrow, but who knows what that will cost. If it's just a broken pin it would be nice if I could just fix it.

Anything else I should check for? I looked at both saddle bags, etc., on either side and everything's fine.