Just noticed this on my iMac that is ~ 2.5 months old. At first you may think it's a glare, but I assure you its not. Is it like moisture or condensation? It is inside the glass. This is from far away. The issue is in the lower right-hand side. It's kind of a wave-like pattern. And here it is up close. Don't mix it up with the glare which is at top. It's still the bottom right corner.