As future human-robot teams are envisioned for a variety of application domains, researchers have begun to investigate how humans and robots can communicate effectively and naturally in the context of human-robot team tasks. While a growing body of work is focused on human-robot communication and human perceptions thereof, there is currently little work on human perceptions of robot-robot communication. Understanding how robots should communicate information to each other in the presence of human teammates is an important open question for human-robot teaming. In this paper, we present two human-robot interaction (HRI) experiments investigating the human perception of verbal and silent robotrobot communication as part of a human-robot team task. The results suggest that silent communication of task-dependent, human-understandable information among robots is perceived as creepy by cooperative, co-located human teammates. Hence, we propose that, absent specific evidence to the contrary, robots in cooperative human-robot team settings need to be sensitive to human expectations about overt communication, and we encourage future work to investigate possible ways to modulate such expectations.