I just got done with Apple concerning my iphone 5c screen. I notice a hairline crack today. The rep told that this is a common occurrence and is covered by warranty. I didn't notice it for a first couple weeks. Keep an eye on your screens!
From what I've read the 5,5c,5s all share the same panel. Honestly I think it would cost apple more to downgrade the screen on this rather than use the same panel as the other two models.