I don't know if this is a blues thing or what but I'll see it a lot in delta blues, Eric Clapton, I've seen Eddie Van Halen use it some and even John Mayer but its like they are going up and down the neck in pairs of 2 notes. Kind of like the intro of "Wanted Dead or Alive" by Bon Jovi

For example, John Mayer does this nice ascend/descend on Heart of life that starts with A7, in tab for that would be 0-2-x-2-0-x and then he'll go to 0-3-x-4-0-x and then 0-5-x-5-0-x and so forth. What are these 2 note melodies called? I know they follow scales and in this case it looks like the G Major scale.