Yes, it's only in bold when there are replies that you have not read. It will also only come up in the New Posts section when there are replies that you have not read. So if you just start it and no one has replied yet, it won't show in New Posts. Also, if there are have been a bunch of replies in other threads more recently than in your post, it could be a few pages deep in New Posts. You can always click "User CP" (on the blue bar that runs across the top of the page) to see all the threads you're subscribed to (including your threads you started), and if someone has replied since you last viewed it, it will be bold there.
