B.C.
I do in-home daycare and let me tell you, the biting happens so fast that it is impossible to always catch it. IF her teacher saw it happen, or found the bite after (if) she cried, then yes, you should have been informed. Keep in mind that not all accidents can be prevented, but only managed afterward, even by the best watchful eyes. I would mention it to them on Monday, just to let them know that need to watching for a biter.