What color is the stain? I've experienced defects in salted prints because the paper hadn't fully dried in one spot compared to an adjacent area. One part would be blue-gray and the other part maroon-gray. I started drying the paper longer before printing on it and that problem went away.
The stain is brownish and usually in the left side. It's in the same shape as the puddle. It intensifies when I wash the print.
"Photography, like surfing, is an infinite process, a constantly evolving exploration of life."