You may have just had 4G compatibility activated. I got it with Amber, it was an extra download though and not actually part of Amber. That isn't the case everywhere, it is rolled out as 4G becomes available (sort of) in your region. Check your phone settings. If it is set to 4G and you don't use 4G (ie. you don't have a 4G data plan) you should limit the phone to 3G for battery reasons (to stop it hunting for a 4G transmitter).