That's too bad. When I first started gardening, my neighbor used to broadcast fertilizer w/ a weedkiller (2,4, D) on his lawn and it drifted over - my garden bordered his lawn - and my veggies (both leaves and fruit) grew very distorted shapes. So it was obvious they were affected. 2,4, D is a growth regulator and it pretty much grows plants to death. When I told him what happened, he stopped using it.
I wouldn't worry too much if your veggies are a reasonable distance from his garden, and/or if you have a fence or hedge. But if you're comfortable approaching him, or know what garden service he uses, ask what they're spraying so you can check it out.
Formerly Kaleicious. I still love kale, but no more than lots of other garden greens too! Orach is currently my favorite.