S.K.
As an in-home provider of 24 years, I can say your questions are valid. You just might not like or trust the answers.
I have had the unfortunate task of dealing with biters. Once I know I have a biter in our midst, I am on high alert. I will shadow that child and put them in a high chair when I have to do things like cook or go to the bathroom.
What you need to understand is that it happens VERY fast. I've seen it and it's come right out of the blue with ZERO provocation. But I've also missed it many times. If I haven't had anyone bite in a long time, I'm not expecting it. If the children are playing happily in the room I am in, I'm very likely to pick up a magazine or book and read a few lines here and there. This might not be what you want to hear. But in most cases, they don't need us to by hyper vigilint every second and most people can't put in a 10-12 hour day without a break in body and mind here or there, unless we have a child that's going through a biting, hitting, scratching or hitting phase. Then we have to be on alert at all times.
As for the crying, you would be so surprised. My initial reaction is heck yeah they cry. BUT, that's not always the case. Last week I had a boy bite one of my girls. He's done it a few times, but the bites were weeks apart and only made temporary red marks. They were also on a finger of a hand that was being shoved too near his face. So I haven't really considered him a biter or felt we were at risk for it. Anyway, he was just being his normal all boy self and leaning over on her during play time and he suddenly bit her on the shoulder. I was in the room, but busy picking up and messing with the babies. She told me he did it with this huge smile on her face. I assumed he barely put his teeth on her to be silly. I mean she was grinning from ear to ear. I found out the next morning that he left a good little bruise!
I've also had kids that don't react the same in all situations. One day they are in a terrific mood, fall and hit their head on something and get up with a smile on their face. Another day the same child is moody and barely stubs his toe and is crying loud and long and wanting a lot of sympathy right now.
One more story and this is on the other side of the coin.... I have a good friend and she made a BIG mistake. When her son was young he climbed in a crib and bit another child 8 times and this was a baby of I think about 6 months. Now her big mistake was 2 fold. One, she put her 2 year old in the same nap room with a baby knowing full well he was climbing out of his crib and had the propensity to bite. But the biggest mistake was that she thought the little girl was crying because she didn't want to nap and she was letting her cry. 8 bites HAD to be excruciating and it seems that she should have been able to hear the difference between being bored and mad that she's in a bed and being in that kind of pain.
Because of what happened in my girlfriends house and all I've seen over the years, I always check on kids frequently when they are napping.
The best thing to do is to ask if she can isolate the time of day it happened. Then ask her if she was cooking or cleaning during that time of day. Tell her that if she has to take her eyes off the kids, be out of the room, or be doing something where she can't really know EXACTLY what's happening, that you want your daughter either in a highchair near her or other safe place away from the kids, or that she wait to do these things until your daughter is napping, by herself, in a crib and away from the kids.
One more thing...she may have hoped you would think it was a scratch. Biting is a HOT, HOT, HOT button for parents. It is HARD to have to tell them a child was bit. Your parents reactions might be normal, but they are terribly unfair towards the provider without knowing the details of how she runs her place. You need to consider the length of service this provider has, her experience, is this her first experience with biting? I've seen as many as 2-3 years pass without a biting incident. Once a bite happens though, it's catching and can really spread fast through a group of toddlers. So even a young provider with 2-5 years of experience could be experiencing this for the first or the 20th time.