I just checked and if you want to add the date you can open up the following file:
\modules\mod_s5_masonry\tmpl\_item.php
And add the below wherever you desire it to output (above the title, below the title, etc):
<?php echo JText::sprintf('COM_CONTENT_CREATED_DATE_ON', JHtml::_('date', $item->created, JText::_('DATE_FORMAT_LC3'))); ?>