I just got my headers coated but now I can't remember is there so posed to be a tiny gap from the header flange and the head of the motor??? I did sand down any overspray on the flange part of the header
the flange is what holds the pipe to the head. if it contacted the head it would not be able to put any force into the exhaust, you would just be squeezing the flange. not only is the gap normal but it needs to be there.