so im sitting here browsing the web with my iphone 3gs plugged in charging with itunes closed and all of a sudden my phone just shuts down and starts to reboot. it stayed on the apple logo a little longer than normal but it seems to have booted just fine. i booted up itunes and it wouldn't connect to my phone. i tried unplugging and replugging the usb cable and that didn't work. so i unplugged the phone and reconnected it and that worked. why would my phone just reboot for no reason.