Trees on neighnors side of fence but mostly hang over my yard, fair to split cost of removal?

He's having 2 trees taken down, but not the ones that are just on the other side of the fence but almost entirely hanging over my yard. He said, eh, if they fall they will just fall in your yard. I can have the tree guy prune everything hanging over the fence, and then he will be left with just the trunks. So I offered to split the cost of removing them both completely. Does that seem proper? He "wants to talk about it" tonight which doesn't give me a good vibe.