jessmfelt on "[Plugin: Pinterest "Pin It" Button] Pin image too small error - even with correct image size"

When I try to pin something using this plugin button it comes back with an error every time - pin image is too small. But I can see that the image is huge (600px+). Any one else have this error? Is it a problem with the plugin, WordPress?

https://wordpress.org/plugins/pinterest-pin-it-button/