Herbicide drift?

So one of my new seedings this year had completely died off - I was pondering whether it was just because it was a super-dry summer here in Mid-michigan, but was really not sure. Was talking to one of the old timers today and showing him the photos of before/after and he was fairly certain that it'd been sprayed. Could it be that the neighbor sprayed dicamba on his beans and it drifted over my hay field? (Edited to add that I'm not necessarily sure it was dicamba, just seems like everyone's using it around here this year on their beans).

 

Seeded it May 20 with 10lb alfalfa, 4lb OG, 4lb timothy, 2lb brome, got pretty good germination - here's a photo on July 27th when I did my first cutting:

 

 

And this is the same field, in a similar location (albeit panorama shot) from November 1, before any frosts:

 

 

I'm really at a loss as to what would cause this apart from drift. It was dry, but we've had a ridiculous amount of rain since about october 1, and there's basically 0 regrowth.

 

It's only on the part of the field that directly adjoins the neighbors field. As you can see on the panorama, the left side of the field in front of the woods is nice and green.

 

Thoughts?

Herbicide drift?