[Ken Case]

Right now the App Store is a little confused: its catalog data thinks v1.0.3 is the latest release, but it's actually offering v1.1 for download. This means that when you download the current v1.1 build, the App Store sees that what you have (v1.1) doesn't match what it thinks is the latest (v1.0.3) and offers to update you again.

The App Store servers will presumably get in sync again soon, but in the meantime you can confirm that you have the latest build by launching OmniFocus, going into the Settings screen, and scrolling to the bottom to verify that the version it lists there is OmniFocus 1.1.

Hope this helps!