We spent most of today tracking this down and think we got it! As it turns out there is a bug in the Corona use of Webviews (logged here http://developer.coronalabs.com/forum/2012/09/06/webviews-not-positioning-correctly)
There is a new SDK on our website (http://lunarads.com) you can get now that should correct this issue for you - please read the updated documentation inside the SDK to insure ads display correctly, or just avoid using web views for now by setting useWebView = false, when calling LunarAds until Corona addresses the bug.
Rich [import]uid: 9046 topic_id: 30612 reply_id: 122944[/import]