IPhone :: Updating Often 4 Bars Down 1 Then Back Up 2

A few weeks ago I updated my iPhone 4 to the new 4.0.1 software. Since then, my phone has been doing something strange. In areas where I always had 4-5 bars with it, my old 3G, my current Blackberry Bold from work, and various other AT&T devices, it will often go from 4-5 bars down to 1 and then back up to 2-3. During this time, my Bold sitting right beside it will constantly stay at a full 5 bars. Now obviously the signal strength depiction is going to be lower after the update as that's what it's intention was. What's strange though is how it jumps around at certain times, will often show 1 bar where my Bold (which isn't the greatest at RF to begin) with stays at the full 5. If I force the phone to 2G only however, the issue seems to go away.

I've tried resetting the phone, network settings,different cases, all to no avail. Does anyone happen to have any insight on this? Is the phone defective, is there something else I can try? It's obviously extremely annoying because when the phone is showing 1 bar, I don't know whether or not there really is low signal strength, or if the phone is simply depicting it wrong.