Broken ribs are notoriously hard to see on X-rays  were looking more for breaks that are also very out of place, or a collapsed lung from the fracture. So you could very well have a broken rib that wasnt seen.
Thank you! Yes all the doctors seem a bit mystified by it. I have follow-ups with the surgeons in a couple weeks so I will get more details. I admit to feeling a bit freaked out by the experience. And the chest pain has been killer.