Since the iso checked out I assume something happened during the burn process, especially since since both the media check and a direct md5sum of the disc don't match the expected. md5sums do fail on even a few different bytes. Usually buffer underruns are detectable when burning, so that probably isn't it. It's possible that no package you installed used those corrupted bytes. Or it could be that some file you installed is corrupted. Maybe verify all your rpm packages with "rpm -Vva". It'll take a while but should check much of what you installed.
