Sorry I sound so skeptical about judges. But I am one, and I know how some are, so...
The big point you need to keep in mind is, sometimes hops are grassy. They just are sometimes.
Dry hopping will give you more grassy flavors than boiled hops.
Also some crops will be more grassy than others.
Certain varieties such as Saaz are known for being more grassy than others.
Also, hops that are not ripe and/or not sufficiently dried will taste grassy as well.
Lots of factors.
Without tasting the beer myself, I am skeptical when judges of unknown qualifications throw out terms like "grassy", because... I just am, based on experience. I haven't experienced a huge lot of beers that are indeed grassy, and one judge didn't even notice or care, which makes me all the more skeptical. But if it's truly grassy, then see above.
Okay I've said everything multiple times now again and again over and over so I'm done now.