Hi MeOnWrdPrs
Can you us the show differences button and take screenshots of what changed so we can look? This will help us figure out if its a hacked file or if this is more of what happens sometimes. A developer may choose to change a readme file to say that his plugin supports up to wordpress 4.0 in the repository instead of changing it as part of a update. SO the plugin on your system shows it doesn't need to be updated when a change was actually made. Mark tells me we actually have all versions of plugins and themes and WP core, so when a developer does that it causes the problem you are having.
Post the screenshots and we'll take a look.
tim