She probably bit way too hard and damaged something from the inside. OR, it could be something you had before. Go see a doctor because any unusual bleeding IS NOT normal.
How much blood came out- was it bright red or just a little darkened urine? If it doesn't clear up by tomorrow, I'd definitely go to see a doctor. all the time there is a bleed between your ureter and blood system, urine is getting into your blood and that is serious! you (she) may have crushed a small blood vessel along with tearing the inside of the ureter. it could be very serious or not at all depending on the amount of blood. Be safe - go to a doctor!