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If your not happy take it back, it doesn't matter how big or small the problem is, you deserve a completely perfect product for your hard earned money.

There is nothing wrong with what your doing, my girlfriend examines the watch i bought her for scratches all the time and freaks out when she thinks she sees a scratch.

If they are not scratches and this has happened already, maybe over time there will be more cracks. Just take it back and say it's not how it's meant to be, simple as that.
 
first pic:maybe cracked, but probably just a scuff as the pictures I've seen of cracked phones(as well as looking on my own), the line was a lot darker.

second: that definitely looks like a scuff mark. Don't worry too much about that.

but I would definitely return it for the light leak. dust CAN get into the phone and onto the screen. Plus you don't want other crap in there anyways.
You paid good money for the phone, you shouldn't have to settle with any sort of defect.
 
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