How could my iPod Touch 4th Generation automatically update its clock when moving between time zones and not connecting to any Wi-Fi networks? I was just reminded of this incident, and was wondering if somebody could explain how this could be possible!

In 2012, I took a flight to America and used my iPod Touch 4th Generation throughout the trip - whilst Airplane Mode was enabled during the flight, when touching down and after collecting everything and exiting the airport terminal, I then disabled this feature so that Wi-Fi was once again enabled. It's important to note that at this point, I hadn't connected or done a search for any nearby Wi-Fi networks, and when checking the time on the iPod itself the device was still showing my local time - and not the new time of the state that I had flown to.

Several hours later, when arriving at my hotel, I once again checked my iPod and to my surprise found that whilst I still hadn't connected to any Wi-Fi networks, the iPod had updated its time to match that of my new location. How would this have been possible if no network connectivity had taken place - is this a known feature? I haven't seen this since (and I've gone to America since this particular trip took place).
I get the pop up message that Bluetooth can improve location acuracy or something like that; maybe you turned on Bluetooth somewhere in that time frame.

Also, referncing the fact that Google maps, and Tetsujin's comments below, Google maps seems to use something that acts like GPS, to tell me where I am while I have wifi turned off. So maybe a you connected using wifi of some sort to a satellite or something else to help your device locate its self. 

Really interesting situation.