Why time functions show invalid time zone when using 'c' time format?

Question

These are the functions I use in my theme to display the "entry-meta" which includes published and last modified dates (among others) of an article:

// Shows Author and Published Date
if ( ! function_exists( 'reddle_posted_on' ) ) :
function reddle_posted_on() {
    printf( __( '<span class="byline">Posted by <span class="author vcard"><a class="url fn n" href="%5$s" title="%6$s" rel="author">%7$s</a></span></span><span class="sep"> &mdash; </span><span class="entry-date"><time datetime="%3$s" pubdate>%4$s</time></span>', 'reddle' ),
        esc_url( get_permalink() ),
        esc_attr( get_the_time() ),
        esc_attr( get_the_date( 'c' ) ),
        esc_html( get_the_date() ),
        esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ),
        sprintf( esc_attr__( 'View all posts by %s', 'the-wolf' ), get_the_author() ),
        esc_html( get_the_author() )
    );
}
endif;

// Shows Last Modified Date
if ( ! function_exists( 'reddle_last_modified_on' ) ) :
function reddle_last_modified_on() {
    printf( __( 'Last updated on <time class="updated" itemprop="dateModified" datetime="%2$s">%3$s</time>', 'reddle' ),
        esc_attr( get_the_modified_time() ),
        esc_attr( get_the_modified_date( 'c' ) ),
        esc_html( get_the_modified_date( 'F j, Y ~ H:i' ) )
    );
}
endif;

Do you see anything wrong with these functions? The problem is, despite setting the time zone of my blog to GMT-05:00 (-04:00 DST) in WordPress Dashboard > Settings > General the timestamp that is output shows GMT+00:00. Any idea why?