Intermittent problem with earpiece and mic

Hi,

Like you probably hear ormsaw one many forums, a lot of iphone 4s are haing trouble with earpiece and mic. When calling or receiving a call, it often happen that I can't hear anything, so I have to put my iphone 4s on speaker and then switch it back to normal to hear what the person on the line is saying. Sometime it works just fine but the person to who I am talking can't hear me for a few seconds (very short time). It is intermittent and as I looked over the net, some people were offering a cheap solution by washing the noise cancelling component next to the audio jack. I will probably go to the apple store to get a replacement phone because it is still under warranty. Anyone has a solution for this problem ?