Bezier curve showing extra "part"

This is easier to describe with a simple image. 

Anyone any ideas why this extra bit is appearing above the top right anchor point and how to get rid of it?

I can't seem to screengrab with handles showing on a mac so to describe. The top right pint has one bezier handle at the same point as the anchor and the other about a third of the way along the horizontal top line. The shape only has 4 anchors, one at each corner and yet this "tab" is generated top right.

Mac and Adobe all fully up to date.

Thanks