Like Yooper's Bob, I too am a wildlife biologist. I believe hops would fall under the non-native or exotic category, but not invasive. That is they can establish here, I've found them growing wild out west, but they aren't outcompeting other species or altering ecosystem function in any way.
That said, I would recommend being responsible in planting. I read some post on here where a guy was "guerrilla" planting hops around the SE which made the conservationist in me shudder.
Oh yeah, and my second year plants are looking great