This is not a huge or site-breaking issue, but rather a minor annoyance and possible bug. So it seems that Akeeba Professional 4.5.3 is incorrectly detecting an update to Akeeba Professional 4.5.3. Reloading the update information from the update server has no affect on this behavior, and I have verified that in fact the newest version is installed and working properly. I cleared the cache, purged expired cache, purged the update cache, logged out and back in, refreshed the update server, and the behavior persists.
I've attached a few screenshots that show the behavior in action.
Thanks you for your really awesome contribution to the Joomla ecosystem!
Best,
Brian