kernel: failed: cg 5, cgp: 0xd11ecd0d != bp: 0x63d3ff1d

I'm seeing a number of messages like the following:
kernel: failed: cg 5, cgp: 0xd11ecd0d != bp: 0x63d3ff1d

and was wondering if it's anything to be concerned with, or whether
fsck(8) is fixing them.
This began to happen when the power went out on a new install:
FreeBSD dns0 12.0-CURRENT FreeBSD 12.0-CURRENT #0: Wed Dec 13 06:07:59 PST 2017
root_at_dns0:/usr/obj/usr/src/amd64.amd64/sys/DNS0 amd64
which hadn't yet been hooked up to the UPS.
I performed an fsck in single user mode upon power-up. Which ended with the
mount points being masked CLEAN. I was asked if I wanted to use the JOURNAL.
I answered Y.
FWIW the systems are UFS2 (ffs) have gpart labels, and were newfs'd thusly:
newfs -U -j

Thank you for all your time, and consideration.

--Chris