MQTT Alarm Interface sends arm on reconnect to broker

So in Brief I am buliding an interface for my wired alarm panel. It uses Arduino 2560 with ethernet sheild and interfaces to the alarm panel via the comms interface , basically a number of outputs that are high/low as states on the panel change.
This then uses PubSubclient to connect to HA using MQTT and is configured as an MQTT Alarm Control Panel. It also sends state information as binary sensors for individual inputs on the panel.

So far so good. Binary Sensors all good.

One issue when the interface subscribes to to the command topic on HA (mosquitto broker) after a reboot or network disconnect, it receives the message ‘arm’ regardless of the current status in lovelace of the alarm panel. After the initial message it works as required.

HA is set to use QOS 0 / retain false. Any one got a clue what might be happening, is this behaviour part of the intergration ?
YAML - below

      name: "I-on40 Alarm Panel"
      unique_id: "ion40"
        - arm_away
        - trigger
      state_topic: "alarm/state"
      command_topic: "alarm/set"
      payload_arm_away: "arm"
      payload_disarm: "disarm"
      qos: 0
      retain: false

Thank you for reading this far cheers Tim