User blog comment:StarlightAT/BLAKE'S BOW TWITCHED!!!/@comment-179.197.52.16-20130906044041

When the scene cuts to Blake and Yang, Blake is already looking up, so she either was randomly looking up, or she heard Ruby screaming. The first would be kind of trolling the audience, while the latter show she has better hearing.

If it was the latter, showing she has good hearing and the bow twitching gives credit to the bow hiding cat ears theory.