It's possible that you had the brake rotor screw holes misaligned with the holes in the hub. There are 5 lugs but only two screw holes so easy to do.

This would have caused the screws to hold the rotor away from the hub when you screwed them in.

 

^^^ What did you use to get such a clean easy looking cut on your backing plate for the brake duct out of curiosity?

 

Sorry. I should have credited that photo. It is from Rob Robinette's DIY for brake ducts. I didn't have any good pictures of my own.

https://robrobinette.com/S2000BrakeDucts.htm

 

Oh ok, thanks much.