Common blues lick and comparable to licks in G that can be heard in Yank Rachell or Johnny Young. When I hear this lick, I think first position E on the guitar, ala Lightning Hopkins or Sleepy John Estes.
This lick drives home the qualities of the 7th chord in blues. It goes from one inversion of the D7 double stop (A – C) where the b7th is on top to a different one (C– D) where the C is on the bottom. Big thing rhythmically is to play it with a heavy downbeat and all pick strokes as downstrokes.
Tablature and other mandolin blues instruction available at Patreon.com