There is a minor error on threadbit pagination. It requires a little more spacing between elements in order to prevent the problem within the attached image.
I think Kier may say it was intentional, but it's always bugged me too. It also tends to interfere with the browser-default dotted border when active (ie, just clicked).
It can't be reproduced with Chrome that maybe the reason you never saw it. For a weird reason chrome ignores the margin value on .discussionListItem .itemPageNav