That she started writing songs rather late in life is both intriguing and, when you think about it, unsurprising. As best I can tell, being "mature" just means that you've got a ton of life knocking around inside you and sometimes the stuff come out: plays, poems, mansions, babies, graffiti, needlepoint, paintings. And songs.
I first saw Mary Gauthier ("go-SHAY") at the Michigan Theater a couple of years ago when she was opening for John Prine. She strode to the center of the stage with her beautiful guitar and, backed by another guitarist, sang a short, strong set that was complete in itself: intense, personal, and wrenching. She's no lilting folksinger; rather, each song felt like a challenge, a line drawn in the dirt.