You know, someone else recently posted a picture that showed something very similar on their hops (which I have seen before). Today, I took a look at one of my plants that had a few leaves that had the same problem. I made a cutting from that plant earlier in the season and planted it away from my main garden and when I checked that one out today, same problem on it. I don't know exactly what it is and it doesn't seem to alter the vigor of the plants, but the fact that it occurred on both the mother and the cutting leads me to think it may be some sort of virus. Doubt it it's anything to be concerned about but I've been wrong before? Hoppy Trails~