Is this clearance for my heatsink okay?

[ferret mocha latte]

Hi everyone,
I bought a NH-U14S for my PC.

I have an i5 2500k and a fractal design arc mini r2 case.

I have a half inch clearance from the top of the cooler to the windowed case door and the fan on the cooler touches to window. It is an exact fit where it does not press against window.

Should this be a concern? Will this affect cooling?

Should I exchange the U14 for the U12?

 

[clutchc]

It should be OK. Is the fan vibrating against the window? If not, I wouldn't worry.