What Causes Lack Of Pain In Foot After Bunion Surgery With Screw?

I had bunion surgery one wk ago. I had 1 screw placed after an L shaped bone fragment was removed to straighten the toe. The bunion, of course, was shaved. Today, I stumbled and caught myself on the foot I had surgery on. The pain at the time of impact was intense, but within a few minutes...nothing. No pain at all...even less then I had before the stumble. Could I have broken the screw loose or could the joint of the bunion moved back out? Those things sound silly, but I guess I'm wondering how this jar could have actually eased the pain?