(I should add that those logs were from `/var/log/httpd/error_log`)
Per the following pages:
https://lists.fedorahosted.org/archives/list/freeipa-users@lists.fedorahoste...
https://www.freeipa.org/page/V4/Kerberos_PKINIT
I found that, somehow PKINIT was... not enabled on my systems? This made very little sense to me, as I'd had no problems before and I DID NOT do an upgrade or anything.