I'm going to second the "solution" suggested above.
The "geniuses" at the Genius Bar will not see what you're talking about, and when they wander off to get a "2nd opinion" you will be shocked to find they return with the first opinion confirmed. They'll run some diagnostics and claim the phone is "performing to specs" and that you are the first person to ever "claim" to have this issue. The genius may or may not refer to this documented, widespread, observable phenomenon as an "optical illusion."
So - don't waste your time with the Genius Bar for this issue.
If you're in the return window, just take it back and tell them you want to exchange it for a new one. If they won't exchange it, just return it and buy the same phone 30 seconds later.
I honestly can't tell you whether or not the techs who looked at my phone had ever heard of this or not. It's entirely possible these guys can't see the problem, and possible further that they personally have yet to encouter it. When I suggested they search the Apple support discussions for "iphone 5s scan lines" so they could see for themselves that this is a real thing, he said they have their own support documents they search and there's nothing in them about the issue. Could be that they are instructed not to acknowledge this problem exists.
Rest assured...you are not crazy.