Where have I heard this song?

I accidentally bought Patty Griffin’s Flaming Red over the weekend. (I was thinking of Patty Larkin. Argh.) It’s one of those happy accidents, because I love the second song, “One Big Love.” (You can hear a clip at Amazon’s page.) The thing is, I already know it, and can sing along. Where the hell could I have heard this song often enough to memorize it? If you’ve seen this in a movie or something, please comment…. the IMDB is absolutely worthless for finding songs like this.