Motorola RAZR2 V9 / V9x

Has anyone had any problems reported to them about their phone? When I'm talking to someone, they will say that my voice will randomly drop off and will be quiet and muffled, as if I had put them on speaker phone and walked away. I can notice a slight difference on my end, but they still sound the same. This problem usually only lasts a little while, but is still cause for concern. I have exchanged for a new one and had ATT download an update to my phone and nothing has fixed it.