http://puu.sh/qr57O/31a3e457d6.gif ( File Mirror:
)What you are seeing is a copy-pasted turret mount that had been sat there for about 10 minutes or so. Upon flying to the underside of the ship, the mirrored version is not present on the bottom of the ship until the camera flies very close to where it is supposed to be.
When building on large ships, it should be the chunks reflect the change to the ship without having to fly closer to force the chunks to reload themselves.
Because I am unsure if this is by design or a bug, I'd thought i'd submit it here just in case.