In Hong Kong, an entire forum thread has been devoted to the problem. So far, there has been no word from LG about the matter. Pictures from LG G3 owners with this issue, all show the same problem, with the same thin crack running through the microphone opening.
If you own the LG G3, has this crack appeared on your unit? Did you attempt to return the phone for a non-damaged model? As news of this flaw starts to spread, LG is going to have to come up with a way to save face, and to also make sure that those with a cracked handset receive a new unit.
Thanks for the tip!