Odd mark at the top of the screen of my new LG V30
I have the same type of defect on my LG V30 but it's on the bottom right corner of the screen
.  LG wanted me to send in my phone for repair, they said it would take 2 weeks, and would not offer a loaner phone in the meantime.  Decided to check with Verizon, and they are sending me a replacement phone by end of week.  Love this phone, and happy that it's a simple swap process.