From what I can tell this issue seems to be similar to the reasons given here: https://unix.stackexchange.com/questions/148144/unable-to-pull-epel-repository-metadata#163368 and not in SL7 or EPEL repos.
My systems are not having that error message now that I've run: yum clean all yum --disablerepo=epel upgrade -y yum upgrade -y
