Isolated stronghold portal room generated in ocean

I generated a new world using the snapshot and spotted a structure generated underwater. It turned out to be the portal room of a stronghold - see screenshot (seed and co-ords included).

There was no sign of any other stronghold structure anywhere nearby and the portal room was "floating" some distance above the ocean floor. This was in one of the new Deep Ocean biomes.

Not sure if this is a bug or just a quirk of this particular seed but thought you would want to check it out.