ports: 11.2 install incompatible with portsnap?

[Gary Aitken]

Haven't seen this on previous releases:

Installed 11.2 release with ports.
Built a large number of ports, then one failed.
Went to update ports tree and it complained:

Looking up portsnap.FreeBSD.org mirrors... 5 mirrors found.
Fetching public key from your-org.portsnap.freebsd.org... done.
Fetching snapshot tag from your-org.portsnap.freebsd.org... done.
Fetching snapshot metadata... done.
Fetching snapshot generated at Wed Nov 14 17:08:26 MST 2018:
55e6e00532155c422c0ee46824a8765642480a924fcc8e100% of   86 MB  368 kBps 03m59s
Extracting snapshot... done.
Verifying snapshot integrity... done.
Fetching snapshot tag from your-org.portsnap.freebsd.org... done.
Fetching snapshot metadata... done.
Updating from Wed Nov 14 17:08:26 MST 2018 to Thu Nov 15 07:19:59 MST 2018.
Fetching 5 metadata patches... done.
Applying metadata patches... done.
Fetching 0 metadata files... done.
Fetching 38 patches.
(38/38) 100.00%  done.
done.
Applying patches...
done.
Fetching 2 new ports or files... done.
root at breakaway:/usr/ports # portsnap update
/usr/ports was not created by portsnap.
You must run 'portsnap extract' before running 'portsnap update'.

Note the next-to-last line:
   /usr/ports was not created by portsnap.

That may be true.  It was created during a sysinstall, but
I don't know what the mechanism used to create it was.

Is this now normal?

Thanks for any insights,

Gary