Why would mt-check.cgi and the System Overview/Tools pages give me different results on the same installation?

In mt-check.cgi it says that some of the optional Perl modules are installed, whereas the System Overview page says they aren’t. Also it shows up an old plugin folder in the includes section that no longer exists, which isn’t there in the mt-check.cgi version.

Very confusing, and probably something to do with the errors I’m getting.

Update: Hmm, well I just checked both pages again and they’re now saying the same thing. I tried clearing my cache and logging out/back in yesterday and they were different.