Thank you for your feedback. Phone is expected to get warm during update as processor usage is high. If you do experience higher amount of heat, we suggest you stop using device and calling Samsung support to replace device.
Mine got hot as well. About the same amount that it does during optimization if I use the Galaxy App Booster. Samsung warns you that the phone may get warm during that process. So, I am guessing getting warm while doing the update isn't unexpected.
