Hi Peter,
This is actually by design and is only temporary. We updated the name of the main plugin file to match the slug of the plugin, to conform to the WordPress standard. The old Main.php file is only there to ensure that the plugin reactivates itself after the update to the rebuilt version 1.0.0. Otherwise, because of the (necessary) file name change, the plugin would not automatically reactivate after you ran the update, which would lead to more confusion and thinking the plugin is broken than a false update warning. Additionally, once the plugin is activated, this update warning should only show on the main updates screen and not the Plugins screen. Nevertheless, this will be removed very soon, as it was only in there temporarily while most sites get updated to the new version 1.0.0.
