You weren't breathing were you?
Depends where on your ribs. What bra were you wearing?, what type of bra?
If you use a 'squash em all in' then is the band to tight.
When I was a teen I used to suffer sore ribs, it's not that uncommon, it was explained to me but I can't remember the ins and outs, this moving against that etc. I don't know how old you are but I think this was an age related thing.