That's known as a parallelogram, I believe. Yes, it's possible. It means you're gantry isn't perpendicular to the other axis.when I take a measurement diagonally to check that my cuts are square they are off by 3/16 but the length and width measurements appear to be the same, any ideas on what might be going on, I didn't think that was mathematically possible?
You didn't post your g-code, but the drawing looks fine.