Looks like it to me. I had the same thing pop up on my phone (in a different spot). Over time, the lines got longer until they spanned the entire screen. Didn't affect the phone's performance, but were annoying. I got a replacement under warranty.
My phone had them pretty bad. It finally got to where the dead pixels were large enough that they were covering spots on the screen so i couldn't use certain features on the phone.
I had 73 days left on my Apple care plan so i sent it in. They had a loaner phone here the next day. That was May 22nd and i still haven't received my original phone back yet.