First off, great plugin. I am in love with this thing.
Secondly, I found a bug in the build/editor.js that occurs when a user is using the_post_thumbnail front-end editing functionality. Basically, if a user uploads a picture and then selects "Change Image" on the initial upload, the image id is not grabbed properly in the JS. I have a patched version on my github fork that you can take a look at here:
Hopefully you can roll in this JQuery selector fix into your next version. I just wanted you to be aware of this. Thanks! Once again, thank you for the amazing plugin.