Bezier curve showing extra "part"

[wazzzzo]

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

[Doug A Roberts · Accepted solution]

Does it change if you switch to CPU mode (View > Preview on CPU)?

[wazzzzo]

It does, completely dissapears.

Any explanation why or should I just rejoice and continue like nothing was ever wrong.

Thank you!

[Doug A Roberts]

I would be relieved that it won't affect your output, but disappointed at yet another GPU preview bug.

[Brad @ Roaring Mouse]

This has been reported by a few people.. In fact I'm looking at it right now in one of my own files: