CentOS - Aug 2018 - Very odd: /proc/sys/net/ipv6/conf/all/disable_ipv6

CentOS 7.5, and on one system, I'm getting:
 setroubleshoot: SELinux is preventing /usr/sbin/sendmail.sendmail from
read access on the file disable_ipv6

ll -Z shows
-rw-r--r--. root root system_u:object_r:sysctl_net_t:s0
/proc/sys/net/ipv6/conf/all/disable_ipv6

I find this peculiar. Anyone have a resolution, or is this a bug?

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