I'm hoping this is the right thread.
I'm fairly new to the S4 coming from an S2. I did root MK2 using SafeRoot method. I should not have tripped Knox or anything like that. I unrooted with SuperSU unroot option. Everything looks OK except the Device Status shows Custom. I haven't gotten the OTA yet, but when it comes in, is it safe to try, or am I going to have problems?