I just put a HD detachable windshield on my Fatboy. The top left knotch doesn't appear to fit all the way over the bushing. It's probably snug enough and I'm sure it's not going anywhere but I'm wondering if it's ok to lube the rubberbushings? Maybe spray them with a little WD40?

 

You really shouldnt have to. Mine fits perfectly, as long as you have the brackets lined up.
I would be afraid to put anything on it that might make it come off easier. I would just fix it right so I am confident it won't come off on its own.

 

When you installed it, did you follow the directions and put the shield on before torquing the bolts?
I didn't and had a similar problem. Had to loosen them up and start over.

 

I did not. I'll have to do that.......

 

silicon works better on rubber and plastic bushings than any type of oil.
spray it on a rag and rub the part with it so there's no overspray.

Tho - as stated - correct installation is a good start too