She was being an exhibitionist. She knew good and d#$%n well there was a chance of her boob popping out. It's quite likely that the person that saw it was who she intended to see it. Now she better not complain if he looks at her chest every once in a while. Let's tell the truth, SHE FLASHED HIM! For comfort, yeah right. Why was the sports bra made?
On another note, I don't see how you guys take ukemi without some sort of support. I took a breakfall once with boxers 'stead of my JStrap and I "felt" it. All the way up to my throat. Over the long run that can't be for your "twig & berries".