My hood noticeable vibrates during certain times for the better part of the past year when idling in drive. When I throw it into neutral, it seems to go away. I recently noticed that it would show up more quickly after close the hood after I finished popping it when the car was still on.

The problem started (to the best of my memory) when I had to have my radiator replaced. I assumed the vibrations were from the two metal pieces holding the radiator to the supports not being in the OEM positions. But, a few days ago, I noticed that if I pushed down on the hood, the vibrations went away or were at least significantly less noticeable.

Is it possible that my hood latch is loose, possibly occuring when the radiator was installed? I'm not sure on the procedure involved in replacing it (had my mechanic do it) but is that piece even touched? Any idea on how I might be able to hold the hood lower (it's not too high by any means however)?

 

I'd start by lubing the hood release cable and latch mechanism, it may be sticking

 

you can adjust the height of the latch. there's two 12mm or 14mm bolts that hold it in place. once you loosen them you can slide the latch up or down. you'd want to move the latch down a hair. if you move it down too much it will stretch the cable release and could give you problems down the road.
this should resolve your problem.