Solved, perhaps. Even though I had borderless printing selected, even though I had the full page size set correctly, the expansion set correctly, and the crop to size selected, there was a setting that had a border set on only one edge. As far as I know, I didn't put it there! But I sure can remove it! Smiley Looking to print a sample shortly.
I have no visuals to go by, but perhaps the one sided border might have been PLACEMENT setting. Use Optimal spaced.