Retro disapprovals are a pain. What do STM?

I had an image that was doing very well for me for about 2 weeks, and for some reason, out of the blue, FB retro-disapproved it. Here is the black and white version.

As you can see, it’s nothing too crazy, just a woman in a bathing suit reclining. I’m just wondering why they would decide it’s too sexual. Also, if I ever decide to run that image again, would that jeopardize my account? What small changes could I make to the image so it wouldn’t be automatically disapproved?

Thanks in a ...