I don't know if anyone else noticed, but whenever the guitarist has a lull in the playing, the bassist character stops playing along as well. The bass chart continues normally, but the character stands there until the guitar comes back in.
Just a minor glitch, and mildly humorous. I assume it's just one little code or sommut that was turned around so the bass animations read that one command from the guitar line instead of from the bassline.
Must not be many Bassist playtesters over at Traveler's Tales.