It it's a manufacturing defect, which is extremely doubtful, it would be on the part of the case manufacturer, which is a cheap one, rather than on the part of the PSU manufacturer, which is not a cheap one.
Can you post a picture of the back of your case and the back of your power supply?
Just for shits and grins, turn the PSU over and see if the screw holes line up. I've seen cheap cases orient the screw holes the wrong way before, so it wouldn't surprise me.