Random Hairline Crack in my MacBook Air screen border/casing?

i was using my macbook today-when i shut the screen there was no damage and when i reopened there was a thick black bar on my screen, i have no idea where this came from thinking it was a softwear errror i rebooted only to find on closer inspection there was a hairline crack/fracture in the lower border of the screen, like so thin you can only just about see it with a torch and my phone camera cant pick it up with the flash on. This is unusual as there was absolutely no obstructions in front of the screen on closure, and after only having this model 2 years im still in the phase where i meticulously dust down/clear the keypad and hinges beforehand. I had a similar issue with my iPad which turned out to be a manufacturing fault and was replaced. With my macbook being no longer under the year warranty is this the same deal as i've been ultimately sold a faulty product?