It happens to people in Walmarts. They're a lot smaller. Certainly could happen with races looking for each other in space with the timescale that energy takes to cross it. Another thing that popped in my mind are the nuclear submarines looking for each other while emitting almost no sound or energy. It's just a void with a tiny piece of data here or there that must be assembled into evidence of others' presence. This can happen even when they're fairly close to each other.