There is a method Zend_Form_Decorator_Label

    public function getLabel()
    {
        if (null === ($element = $this->getElement())) {
            return '';
        }

        $label = $element->getLabel();
        $label = trim($label);

        if (empty($label)) {
            return '';
        }

        if (null !== ($translator = $element->getTranslator())) {
            $label = $translator->translate($label);
        }

When

 is called the element asks his translator to translate the label. But this is also done by

a bit later. We have two calls to translator instead of one.