How do you tell if there is cracks on the back? Since the 3g and the 3gs seem to have this issue. I have the 3g but in black. I can see pretty well but my vision isn't the best (long story but blind in one eye from an car accident when I was younger so some things are just harder for me to see) Since this is covered under warranty I just wanna make sure how to tell for sure so that the issue doesn't escalate. Im NOT one of those people who takes something in for every little thing. Just wouldn't want those cracks to get worse.