Whacky iOS 7 bug that causes App Store apps to exit, wiggle, and then relaunch. I tried it on a number of devices, and while it didn't work on Apple's built-in apps, or on legacy iOS 6 apps, it worked consistently on App Store apps updated for iOS 7. Caught on video by Dan Weeks (via Mike Rundle).
For me, it caused a folder to go into jiggly mode as well. Likely to get fixed in 7.1, so have fun while it lasts, or until you're bored.