Curious about that too TH1 since the song has been around for quite a while. 
Notes at bottom of page might hold a clue - would be surprised it it is just now getting airplay so maybe the Avetts / the song are new to this tracking system ? 


<i>(off topic:  probably overreaching the intent but am amused by the use of Cherry Herring in the Colbert Bump cocktail)</i>