That's what that "little face" being present in the left-most icon means (that you've posted in that topic before)
I learned something today 
I really, really hate the trend of having to guess the meaning of icons (and that's a lot worse on any "modern" website than it is on Bitcointalk.(In an upcoming patch, I'm considering making those face-containing icons clickable: The idea would be that when you click on it, it would open the topic, but with just your posts visible, so that you can easily see the things you've already said in that topic.
Will that also work on very long topics?