An update: I spoke to someone who is in the Corporate Executive Relations department about the issue with the flickering/static lines over the phone this afternoon. I asked her if it were alright to share the details with the community & got the green light as it is their official stance/reply on the matter. As many have posted -- Apple isn't one to usually issue statements concerning all problems that arise. I think they may have only done it twice in the past that I can recall.
She said that Apple is aware of the issue & that they're working on it. It will be patched in an upcoming iOS update. It's confirmed to be a software issue. Why it only happens on some devices, she didn't have details. The bottom line is that they're working on it now & we will have a solution.
Exchanging out the phone will not specifically solve the problem, which is why many people have had the same thing happen in their replacements. Please note that I talked with her about the static lines when inserting password in the App Store, pulling down folders, & at certain times when I have experienced the glitch (such as when the semi-transparent, dark keyboard is pulled) & not some of the other additional quirks some users have expressed in this thread.
I'm very happy I decided to wait it out.