I've had a 3GS for about three weeks, which replaced an old, old Sony flip phone. The Sony was dying quickly and no longer suited my needs, but I have to admit, it almost never dropped a call. I've made about 30 calls on my iPhone in the past three weeks, and I've had 5 drops. Not a huge number, but I hope it won't continue to be that high of a percentage. Is the 3GS known for being sensitive to poor signals? Or, is it more likely that I just had a run of bad luck last week?