I have one of the so called popular F450 frames. Not the original dji one, but chinese part. Now, I have assembled motors and ESCs. The assembling process was harder than it should be, probably because of not being original product. Anyway, I achieved to match holes with each other and installed the top plate. However, there is a problem. To cross legs(front left and rear right) cannot touch to the ground at the same time, i.e, one of the legs stay in the above the ground, approximately 2 cm. Is this something I should worry about? Can a neat flight be achieved with this problem existing?
Do not worry, I also have an F450 frame(not original) and one or 2 of the legs stick up slightly. I have had a perfect flying experience even if I was using an Arduino as a Flight Controller. Your FC(Flight Controller) should smoothe it out. But, if it sticks up more than like 5cm, then you might have a slight concern.