Samsung Galaxy S3 microphone issue

I just realize, my six-month-old Samsung Galaxy S3 LTE does not work. Actually it seems to be working, but no one can hear me, however I can hear clearly.
I run a few tests:

• works fine with car-kit
• noise reduce off
• mute mic. off
• signal ok

I haven't installed any app recently, so it shouldn't be a problem at all. I googled a little bit and found some blogs, where guys got the same issue. So, I'm not the only one.. I made some test calls and I noticed that some noise comes through the lines, means mic might not totally dead. I checked the hole at the bottom of the phone (next to the microUSB port) and put a pin into. Well ... after that, magic... my phone works again.
It looks like Galaxy S3 has some design issue, the mic hole isn't really "pocket proof".