I had a baby of "that mom" who's baby (13mos) bit twice on his last 2 days. Once it was me on my leg and the other was a 4yr old's ear. I told mom the 2nd time because I wasn't going to be like "Um your baby bit me!" Ya know? But with another child I definitely told her and said to watch out for that with other kids he may be around since she was staying home with him. She said something about him biting her in the past couple weeks and I just KNOW if someone bit HER baby she would have yanked him out of here so fast his head would spin but when it's their child it's somehow different.
I totally know how it feels to have my own baby bit or hurt because it's happened as well but we did what we could to prevent it. One little boy was about 18mos and bit my then 4 month old's foot and broke the skin!
I had put him up in the high chair in the kitchen with me while I made lunch to prevent him being on the floor near the biter. He was being good and then all of a sudden I heard that cry, it only took a second. I almost cried myself. It was awful. Thankfully it was his last day as well! LOL it happened 2 or 3 times total with that boy but my DS was a problem biter for about 3 mos last summer at 18mos; teething and not really talking yet.