Inconsistent reporting of missing doc comments

I've corrected all the other problems reported by `phpcs --standard=Drupal --extensions=php,module,inc,install,test,profile,theme template.php` and the last two look like a bug to me. This code:

function k2tech_preprocess_page(&$variables) {
  if (isset($variables['node'])) {
    $variables['theme_hook_suggestions'][] = 'page__' . $variables['node']->type;
  }
}

function zen_id_safe($string) {
  if (is_numeric($string{0})) {
    // If the first character is numeric, add 'n' in front.
    $string = 'n' . $string;
  }
  return strtolower(preg_replace('/[^a-zA-Z0-9_-]+/', '-', $string));
}

Results in this report:

FILE: template.php
--------------------------------------------------------------------------------
FOUND 2 ERROR(S) AFFECTING 2 LINE(S)
--------------------------------------------------------------------------------
 102 | ERROR | You must use "/**" style comments for a function comment
 108 | ERROR | Missing function doc comment
--------------------------------------------------------------------------------

It seems to me that both functions should have the "Missing function doc comment" error.