Checker component - preview issues

I just ran into an interesting issue using the Checker component. In parts of a filter I just released I use a solid filled checker to generate a rotation map (Rotate Madness).

The reduced preview image does not match the output of the full sized image.

What it boils down to: how does the Checker sample the block to determine the solid fill color? I created a test using the same image scaled to different sizes. My conclusion is that when there are more pixels Checker returns a slightly different result. Not normally noticeable but when used for rotations...

Anyone have any thoughts or ideas on this? GMM?

Thanks. The center pixel is what I thought it was. Definitely not a bug. When previewing the center pixel may slightly differ between the preview and the full sized image.

The workaround: uncheck Tools / Options / Interface / Reduce image size for large images

Rotate Madness is pretty fast, so this works fine.