Not sure when or why it was removed. I'm not even sure if it was there! Syahir?
You can still add rel="author" for post author profile link by editing loop-single.php. Replace
$author_url = '<a href="' . get_author_posts_url( get_the_author_meta( 'ID' ) ) . '" class="url">' . get_the_author_meta( 'display_name' ) . '</a>';
(93rd line) with
$author_url = '<a href="' . get_author_posts_url( get_the_author_meta( 'ID' ) ) . '" class="url" rel="author">' . get_the_author_meta( 'display_name' ) . '</a>';
If you don't want to edit parent theme files (and you shouldn't), hide post author in Graphene Options and add this to child-theme's functions.php (untested, should work though)
function my_author_link_with_rel() {
?>
<p class="post-author author vcard">
<?php
$author_url = '<a href="' . get_author_posts_url( get_the_author_meta( 'ID' ) ) . '" class="url" rel="author">' . get_the_author_meta( 'display_name' ) . '</a>';
printf( __( 'by %s', 'graphene' ), '<span class="fn nickname">' . $author_url . '</span>' );
?>
</p>
<?php
}
add_action('graphene_post_meta','my_author_link_with_rel');