Hey Rune7 I just came across this error (warning) too when I try to preload Admob interstitials. It seems to be related to LSApplicationQueriesSchemes where Admob needs to check to see if a particular app is installed or not so it is not showing ads for installed apps.
-canOpenURL: failed for URL: "kindle://home" - error: "This app is not allowed to query for scheme kindle"
After some digging is seems that the bug was fixed in version 7.5.0 of the Admob SDK (native). I am not sure what version the Corona plugin uses but I believe it may be previous to 7.5.0.
References / Google links
https://github.com/floatinghotpot/cordova-admob-pro/issues/224
http://stackoverflow.com/questions/30848208/new-warnings-in-ios-9