Hello, my friend,
Very sorry about this message. The problem is that NginX does not allow us to identify its presence very easily and in a definitive and consistent way, so we make the assumption that user is using the most popular web server nowadays, which is Apache.
However, can you confirm that the message is only displayed in the plugin settings page and throughout the whole admin area? Because this would make it really annoying and should definitely be fixed!
Cheers,
Takis