Another iPhone 4 issue?
 

I'm not sure if this is specific to my iPhone or if it's a bigger problem. When I switch the phone to speaker and try to have a conversation, I can hear the other end just fine, but they say my voice becomes garbled. Take it off speaker and everything is fine. A test earlier in my house seemed to be okay, but another test in my car and the problem returned. It worked for the first part of my call, but as soon as I started to move (I was at a light) my voice garbled.

Anyone else having this issue?