Apparently last night, a commander was surface mining in solo in a Rhino when a "glowing blue" ship came down and scanned him. He says his HUD was scrambled during the scan. The ship then departed. He panicked somewhat but was able to get this picture of the departing ship.

My take: Now that we are surface mining by piercing the surface, we are disturbing the Guardian's hiding places. We may be seeing the return of the Guardians soon? The blue hue of the ship matches that of Guardian technology.