Several pundits have published reports suggesting that there's a bug on the iPhone 5 and the fifth generation iPod touch that prevents response to touchscreen input after a user rapidly swipes his or her finger across the screen, diagonally. I haven't been able to duplicate the issue on my iPhone 5 here in the TechnoBuffalo offices, but our own Brandon Russell was able to recreate it. He doesn't seem to worried, however. "It stopped a little, but I'll never ever [make that motion]," he explained to me. "Once I took my finger off and put it right back it was fine."
TheNextWeb suggests it could be caused by Apple's implementation of a software feature that prevents a user from accidentally scrolling on the screen with his or her thumb, but also points out it might be related to the new in-cell displays used on the iPhone 5 and the fifth generation iPod touch. For now, however, it appears there's no real explanation.
Sound of in the comments if you're affected by the bug and we'll keep you up to date with any movement on the problem.