Similar question was posed on another forum with hops showing a distinct upward curling. It could be the result of 2,4-D or other herbicides used in weed and feed fertilizers. Even if you were careful not to over spray, hot, humid conditions cause some herbicides to volatilize and affect your hops from some distance. This is the first year mine didn't curl as I applied the weed and feed stuff much earlier this spring.
I hadn't thought about that but my neighbor sprayed his lawn with weed killer not long before this happened. I wonder if the wind could have carried over into my lawn and near the plants. I'm only 15 feet away from his yard.