Ah, that explains it! I was thinking "Monroe Brothers" even though you said James on the link. I went and listened to Rowan's and yours doesn't sound like him after all. It really is a great song. (We just started doing it in our band, and I got stuck finding a baritone part, since the other harmony singer couldn't. So far, that hasn't ruined the song).
Thanks again. It's always nice to find another bluegrasser.
As to who invented bluegrass, I feel like it's me and the people in my jam, every time . . .