Maybe because the ambient temperature is low in aus? Mine takes a minute and a half tops to show a reading on the temp gauge.
By grumpy I meant it is idling at 1000rpms, It settles on 750rpm in 4-5 minutes. If I'm not in a hurry I let it idle till rpms drop to 750, if I'm in a hurry I pull out as soon as a reading appears on the temp gauge