Do you own an iPhone 4? Then good news. The antenna issue that's been bugging iPhone 4 users might be fixed pretty soon. iPhone will release a phone software update in a couple of weeks to correct the issue. Accordingly, the iPhone 4 incorrectly calculates the number of bars to display on the iPhone.
FYI, some iPhone 4 users have reported that the iPhone 4 drops 4 to even 5 bars when tightly held in a way that covers the black strip in the lower left corner of the metal band.