Using luma key for video transition

I downloaded a free transition from Stock. It starts off with black and then colored shapes fly around and then back to black. So I used the luma key to key out ther black to make the transition. See below screen shot.

It looks clean overall but there's an ever so slight black edge around the colored shapes, so I just wanted to make sure this is best way to get rid of black or is there a better way to do this? Any advice is appreciated. Thank you.