<?php
/**
 *    Source & Inspiration: 
 *    https://wpengineer.com/1913/if-post-is-older-than/
 *
 *    If a post has not been updated within the last 60 days place a notice to alert the reader
 *    For placement in functions.php of your theme or child theme.
 */
 
function jd_is_old_post($days = 60 ) {
	$days = (int) $days;
	$offset = $days*60*60*24;
	if ( get_post_modified_time() < date('U') - $offset )
		return true;
	
	return false;
}
?>

<?php
/**
 * If post is older than 60 day's this will post a notice to the reader
 * For placement within the loop of the post.
 */
if ( jd_is_old_post() ) {
	echo '<div class="old-post-notice">';
        echo '<p><strong>This page has not been updated in 60 days. The information below may be outdated.</p></strong>';
    echo '</div>';
} 
?>