Message notification won't go away?

Hi! New to the site, and I posted my first giveaway about a week ago. Someone commented on the giveaway (just a generic "thank you") and I have a message notification in the little control panel bar at the top of the site - when I clicked on the notification, it takes me to my giveaway and the comment in question. But it won't go away - how do I tell the site that I have read this comment and no longer need the notification? Is there something I am supposed to do that I am missing? When I view other peoples' giveaways I see lots of "thank you" comments on them and no replies, so I don't think I am supposed to have to reply to every comment.
Any tips would be appreciated, thank you! ^_^