Southdowns will generally look good at this time of year, due to good fleece growth. Have you condition scored them? If they were used to being given hard feed regularly they'll yell if they don't get it, until they realise that your appearance doesn't always mean food. My ewes are getting hard feed in the run up to lambing but if I go into the field for another reason I hold my hands out to the side so they can see I'm not carrying a bucket, and then they carry on with what they were doing before I walked through the gate.