Unequal surface offset

Hi, I’ve attached a file in which a surface is offset as a solid.
Although the offset keeps the desired thickness,
it doesn’t finsh the edges equally on both sides of the finished object.
This gives unequal dimensions (in dark blue).
Although the source geometry is symetrical.
Is this normal for the extrude surface function to only have a limited precision?
The descrepancy is greater than my document property settings.
Unequal_Offset.3dm (240.9 KB)

Hello- the curve is slightly asymmetrical.

Mid point:


Ah, ok thanks.
I should remember the ‘control’ points can be used to check. I was just going by the end points.
Found my problem, was using a different software package to create the curve.
The one control point was a ‘mirror’ of the other being multiplied by -1.
But I forgot to specify the value as a float so it rounded down to the nearest whole number.