Originally Posted by
FBinNY
it'll only be less wrong, which isn't the same as right.
Not speaking to the case at hand, but when "less wrong" comes within tolerance, it IS "right".
The builder should make this right being it's a new frame. That being said, if one runs across this on a used bike, a 31.8 (which used to be a common size before aero became a thing) a post that size, and a more appropriate clamp will solve the issue.