I've been seeing messages like this a lot lately:

/etc/cron.daily/0yum-daily.cron:

Not using downloaded sl-security/repomd.xml because it is older than what we have:
  Current   : Thu Aug 23 10:00:16 2018
  Downloaded: Thu Aug 23 10:00:13 2018

-- 
Orion Poplawski
Manager of NWRA Technical Systems          720-772-5637
NWRA, Boulder/CoRA Office             FAX: 303-415-9702
3380 Mitchell Lane                       [log in to unmask]
Boulder, CO 80301                 https://urldefense.proofpoint.com/v2/url?u=https-3A__www.nwra.com_&d=DwICaQ&c=gRgGjJ3BkIsb5y6s49QqsA&r=gd8BzeSQcySVxr0gDWSEbBYBgsCHS7vSr83lHQ-aa58eXICk1KkzZlAHgohLRRrX&m=v8UxhACHw-HDM-R1JFcbT2LDwhcByIcgK6rlK3jaREY&s=mMF9WQVhgX_U7xqGxe5xn4G65Ge56foX0T-1Ox18X9M&e=