@Override
  public synchronized void nodeLeft(GfManagerAgent source, GemFireVM left) {
    InetAddress hostIpAddress = left.getHost();
    List members = (List) hostMembers.get(hostIpAddress);
    if (members != null) {
      members.remove(left);
      if (members.isEmpty()) {
        // No more members on the host
        hostConfigs.remove(hostIpAddress);
        hostMembers.remove(hostIpAddress);
      }
    }

    okayHealth.remove(left);
    poorHealth.remove(left);

    reevaluateHealth();
  }
Makes note of the newly-left member
geode-core/src/main/java/org/apache/geode/admin/internal/GemFireHealthImpl.java