thank you

and i am on bootload it says ***l0cked(00w)** at the very top
ok so you are correct in that you are not rooted as you have a locked bootlaoder. so the ota should be fine by accepting it. the only thing that i can't be sure is if your flash will stick as the ota will contain new radios.
for now i would not accept it, until you get confirmation that it will not mess with your flashed phone. so i would go into settings>software update>uncheck the option to check for updates. now you should not get the message that you have an update.
once you get confirmation that it will be fine then you can go back and accept the ota.
maybe ask the place where you got your phone flashed and ask them about the ota. they should know.