HTTP error code on page from aws_signed_request.php file

Hi,

I am suddenly getting the following error message at the top of my page that contains the Amazon products:

Warning: file_get_contents(https://webservices.amazon.com/onca/xml?AWSAccessKeyId=AKIAIASC5AMKLIO47H3A&AssociateTag=aboutface0a-20&IdType=ASIN&ItemId=B0064XSQ8A&Operation=ItemLookup&ResponseGroup=ItemAttributes%2CImages%2COffers%2CReviews&Service=AWSECommerceService&Timestamp=2014-02-21T04%3A42%3A50Z&Version=2011-08-01&Signature=jyTBWIiDY1NsxpVlVr25J6mueu8qYTJkESGBj9o738M%3D) [function.file-get-contents]: failed to open stream: HTTP request failed! HTTP/1.1 503 Service Unavailable in /home/aboutfacesf/new.about-face.org/wordpress/wp-content/plugins/amazon-product-in-a-post-plugin/inc/aws_signed_request.php on line 376

The products are still appearing on the page, and appear to be working fine, but I’d love to get rid of the error message. Can you please advise me how to do this?

The page in question is http://www.about-face.org/educate-yourself/learn-more/

Thanks
Tessa

https://wordpress.org/plugins/amazon-product-in-a-post-plugin/