iPhone 4S searching bug

I have an iPhone 4S and iPad 2 3G.  Both with AT&T.  I've had the 4S since it came out.  I'm not sure when this started (a month or two ago), but when I turn off my iPhone and turn it back on again, it sits in searching for a minute or so and finally finds a signal.  Once it gets a signal it's okay (ie it doesn't lose the signal), also putting the phone in airplane mode and out only causes a search for a few seconds.  Only powering it off and on causes the long searches.

My iPad 2 doesn't have this problem, only the iPhone 4S.  I've tried resetting the network settings (which fixed a problem with the iPhone 4S not downloading any faster than 2 Mbps), but it didn't fix this problem.  The iPhone also has a much higher latency (ping) time than my iPad recently as well.

Any ideas why this is happening?