Unpinning a topic is seen as an action so it counts as a new event in the topic.
Are you talking about the one done in the last podcast episode? Ep. 364 - Way More Chooms, with Kieron Gillen - #58 by Hunter
I am unaware of a system change to fix it, but I believe if a member of staff deletes the action it should not appear as a new event.
I can try something later today to be sure. And am also looking into the profile pic thing as well.