Can you see the Newton Rings already on the photographic print or is it at first on the scanned result ? In that case it could possibly be Newton Rings from the contact between the print and the scanner glass. I know it sounds improbable as the print surface seldom is flat enough unless you ferrotype the print or use glossy RC-paper. It can be worth looking into.
I attached a picture to a post above where I've marked the rings in red.
"Often moments come looking for us". - Robert Frank
"Make good art!" - Neil Gaiman
"...the heart and mind are the true lens of the camera". - Yousuf Karsh