Please make sure you have populated all the icon fields in the Properties page of your project - both for iPhone AND iPad, even for apps targeting only one or the other. Even though I can't find anything official in the iOS 7 pre-release docs, it appears that the App Store.app and Spotlight now use a different set of icons to preview the app in listings.
This doesn't mean that the app's icon you published it with has suddenly changed - the icon is the same, it's just that the OS now respects another one of all the icons iOS requires. Please unzip your IPA package and check out all the icons inside - if you haven't changed any of the default icons in Project Properties, its Icenium placeholder will be placed there instead.
tl;dr - Please double-check that ALL the icons in your project are the ones you expect, not the Icenium wire-frame image.
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