I'm not a coder or know code in any fashion, but the way it lines up with the end line of the above page box (that light grey line at the bottom above the purple box) makes me think it's some kind of limitation/containment error. That and the parenthesis gaps. Not sure if that's also intentional or not (they're in every instance barring the line for threaded/top-level comments, so I wonder about the implementation on that as well)

I just thought I'd bring it up since it happened immediately after the inbox 'reroll' and not before, and it doesn't have a numerical value (first box has page numbers in 10s, second has it in 21s)

Edit: Testing something here since I notice a large gap in the username/userhead graphic used in the post, so I'm doing it to mine memester to see if that's an issue or just a one off in the post.