I found that the rendered HTML from this (awesome) plugin didn't quite make it through the W3C markup validation.
A small fix of adding a alt attribute to the image tag on line 336 of genesis-responsive-slider.php and properly closing the tag fixed it for me.
"My" line 336:
<a href="<?php the_permalink() ?>" rel="bookmark"><img src="<?php genesis_image( "format=url&size=slider" ); ?>" alt="<?php the_title(); ?>" /></a>
Can this be fixed in an upcomming release?