Unread indicator snafus

I might be the only one with this problem, and it's just a nagging thing, really. Any tips would be appreciated.

I access the board through kindle and iPhone. On the iPhone, a lot lately, the unread indicators on the threads (blue triangles) are grayed and the actual unread posts are not bold.

Since I'm really addicted to keeping up on the posts, any pointers would be greatly appreciated. Doesn't seem consistent, either. Worked fine all day yesterday, but not today.