[Plugin: Carousel-of-post-images] Conflict with Relevanssi

If I have both carousel-of-post-images and relevanssi plugins activated, when updating a page that includes a carousel-of-post-images (even if nothing else) then I get the dreaded “cannot modify header information – headers already sent by (output started in /home/pippa/www/www/wp-content/plugins/carousel-of-post-images/main.php:58) in /home/pippa/www/wp/wp-includes/pluggable.php on line 866”

Of course it could be a relevanssi issue, but could you check please. It is 100% repeatable.

http://wordpress.org/extend/plugins/carousel-of-post-images/