No 9x6 is a 3:2 aspect ratio. 3:2 aspect ratios are image with sizes like 3x2, 6x4, 9x6, 12x8 any image size that has side sizes that have 3:2 ratio. Are you sure your camera has a 3:2 aspect ratio most DSLR have a 3:2 aspect ratio. Most point and shoot cameras have a 4:3 aspect ratio. If you have a 4:3 aspect ratio camera and you resize its images to 3:2 aspect ratio what you seeing will be the result.
Your 40.98 x 27.43 is very close to 3:2. 40.98x27.32 and 41.145 x 27.43 are 3:2 aspect ratios. What Camera do you use and do you use only one camera?