i've been noticing on multiple occasions that my iPhone 4 has lower signal strength than my girlfriend's 3GS in the same location. for example, in my home, i get around 4 bars on the iPhone 4, but my girlfriend gets a consistent 5. the other night we went out to a restaurant and my i4 would fluctuate between 3-4 bars while hers would be at 5. what gives? i wasn't even death gripping the phone. any ideas? both phones are running iOS 4.0 btw.