A hairline micro-crack in the middle of the plastic part (antenna) of iPad 2018 (6th gen)

Hello,
Just wondering if anybody is facing the same problem. I had just bought an iPad 6th Gen (2018) Cellular 32G 11 days ago. Yesterday, when I took it out of the case, I noticed a micro-crack in the middle of the plastic part on the back of the iPad, right on the opposite side of the camera. There was no drop, no physical damage. Is it possible that under some kind of pressure or temperature the plastics cracked inside out? I was using video calls, and it's known that during the video call the camera becomes really hot. I've already brought it to one of Apple authorized services and now waiting for their diagnostic result.