That happens very often when updating style for latest version of XenForo or any add-on - sometimes there is nothing to change in template other than bumping version number.
Issue is caused by template data writer. It updates last_edit_date only if template content was changed, ignoring changes to other properties. I think it should update last_edit_date when version_id is updated as well.
Fix: in library/XenForo/DataWriter/Template.php find
if ($this->isChanged('template') && !$this->isChanged('last_edit_date'))
if (($this->isChanged('template') || $this->isChanged('version_id')) && !$this->isChanged('last_edit_date'))