Title repeats on every post

The problem:
I’m pulling 4 posts to display the date, title, and excerpt on my main page. Everything works just fine if I put the code directly in my index.php file. But when I create a function for it in the functions.php file, the title from the most recent post is displayed as the title for all 4 posts.

Here’s the code that works fine in the index.php file:

<?php
$args = array( 'numberposts' => 4, 'order'=> 'DEC', 'category=-1' );
$postslist = get_posts($args );
foreach ($postslist as $post) :  setup_postdata($post);

$mydate = get_the_date('F d', '', '',FALSE);
$expdate = explode(' ', $mydate);

$month = $expdate[0];
$day = $expdate[1];?>
<div class="dateBox">
<div class="ramblingDay"> <?php echo $day;?></div>
<div class="ramblingMonth"> <?php echo $month;?></div>
</div>
<div class="ramblingTitle"><?php the_title();?> </div>
<div class="ramblingExcerpt"><?php the_excerpt();?></div>
<?php       

endforeach;
?>

And here’s the code for the functions.php file. Only thing that is changed is a function wraps around the previous code.

<?php
function display_ramblings(){
$args = array( 'numberposts' => 4, 'order'=> 'DEC', 'category=-1' );
$postslist = get_posts($args );
foreach ($postslist as $post) :  setup_postdata($post);

$mydate = get_the_date('F d', '', '',FALSE);
$expdate = explode(' ', $mydate);

$month = $expdate[0];
$day = $expdate[1];?>
<div class="dateBox">
<div class="ramblingDay"> <?php echo $day;?></div>
<div class="ramblingMonth"> <?php echo $month;?></div>
</div>
<div class="ramblingTitle"><?php the_title();?> </div>
<div class="ramblingExcerpt"><?php the_excerpt();?></div>
<?php       

endforeach;
}
?>

Thanks everyone in advance