I think that Ms. Weymouth's nervousness might have something to do with this:

The Talking Heads had been going around trying to con bass players to join the band but everyone said, "Shove off, you uncool geeks." (Or words to that effect.) So they gave Weymouth a bass and taught her how to play.

In the notes for a song, "This Must Be The Place" on a compilation called "Sand In The Vaseline", she notes: "We jammed to create this song. I played guitar (I don't really know how to play anything, so it was all the same to me, whatever instrument I played)..."