I noticed that too. That's because it's using a cached clone of the post bar.
The votes are registered though, so it's not really an issue.
If you vote and then refresh the page, the floating title will reflect the vote you previously casted.
Yeah no drama just thought it was something :-)
Not a webdev but couldn't you refresh cache when you get to the scroll point that causes the post bar to move?
The post bar is cached only once when a page is loaded, so it doesn't drain on the browser's resources (especially on mobile).
I prioritize resources over OCD ;)
(post is archived)