In this blog entry of Bear McCreary, Bear talks about the use of bluegrass music in the episode.
“I knew that southern blues instrumentation would be a big part of “The Walking Dead” sound. I wanted to represent the geographic location of the story, without overtly calling attention to the score.”
Bear also breaks down the choice of music in different scenes. You get a sense of why he chose certain musical queues and how they are to evoke emotion with the viewer. This is a must read for fans of the music of The Walking Dead.