the_excerpt does not update when get_posts

Hi,

I am trying to display a random page from a parent ordered by rand.

the_excerpt shown the first time the page loads is correct then wont refresh / update again. The other elements retrieved, title & permalink, both update when the page is refreshed.

I am using the code below … fairly new to PHP & WP.
Any help appreciated, thanks.

<div class="service-box">

		<h3>Services</h3>

	<?php $rand_posts = get_posts('posts_per_page=1&post_type=page&post_parent=35&orderby=rand');
 	foreach( $rand_posts as $post ) : ?>

    	<div class="inner">
		<span><?php the_title(); ?> </span>
		<?php the_excerpt(); ?>
		</div>

		<a href="<?php the_permalink(); ?>" class="button">Read more..</a>

 	<?php endforeach; ?>

</div>