That's actually part of the whole top-down style. The upper 'plates' are surrounded by a brighter band of color before end and moving into angles.
Now, he chose to do a smooth, flat ship, something not terribly good for a beginner to try in terms of top-down. Blocky is best, and I've told him this already, but to no avail. So it may look a bit off for a while until we help him figure out what he's doing.
But the bright outline isn't his fault.