If there are any active reports, the "report light" on the moderator bar will always be red after you log in, even if you've read all the comments before. This is confusing my moderators!
This is the case in XF 1.2.2, though probably in older 1.2.x versions as well.
I will add too that the report light looks very similar to the alert notifications in the top right. Maybe it would be better if they were more different? Just a thought.