as long as the LED is working and the color is correct, then you shouldn't bother with it.
And unless you have the PC right next to you on the desk, you're not going to really see it.
But if you absolutely must have it perfect, you should reach out to the person you got it from to ask what may have happened and let them know that the only reason you want to know is so you can determine if it'll still be able to be RMA'd under the warranty so that they are honest with you.
And if they've done nothing to have made this happen and it's just a factory defect, then if it means that much to you, you can check to see if it's still under warranty by entering it's product number at this website and then you can send it in for an RMA to either get it fixed or replaced.
Simply create an account then go through the steps to check for warranty on the device.
https://ggcs.gigabyte.com/GIGABYTE-RMA-Login-User.aspx