Had the same thing happen to me on a bag I was making. I used steam a seam to hold some seams together rather than pins or clips. The seams weren't steamed, just used heat as I was just needing to hold something in place. When I turned the bag, some of that steam a seam was visible. Tried the alcohol and it worked great. This was on cotton and organza, didn't leave any marks.
I was surprised I didn't see more posts on this when I goggled it. But glad I found this one.
Stacey in South Carolina