I assume you are aware, but I have been multiple threads where the “new comment above (or below)” flag appears, and the comment shows up as being an hour old.
Interestingly, this happens even when the comment in question is a reply to a comment that is minutes old. When I refresh the page, the new comment that was previously shown as “an hour old” shows up as being posted x minutes ago, reflecting the how long ago it was actually posted.
Happens on my laptop, my ipad, and my iphone. Any idea what is going on?