I have been one both ends. My eldest was the subject of a persistent biter. He still has two scars from it 2 years later. However, saying that, the daycare were very proactive in separating them and ensuring they only spent minimum time together. They also saw it was a symptom of other issues for the boy and talked to his mother who agreed to get his evaluated as his development was much slower than the others his age. As long as it was dealt with immediately and steps taken to ensure that it should not happen again, I was satisfied. After all, it is a normal stage in development for many children. Carers and I also talked to my son to make sure he knew it was nothing to do with him and help him understand the other boy needed help.

My youngest was the biter. This was mortifying. Even though they couldn't tell me who the other children were, I just made sure I loudly asked the other parents who my son had bitten so I could personally apologise. They seemed to like this approach and many were pleased that I personally spoke to them about it. DS2 grew out of it after about 5 months and now only bites when his brother won't get off him when they are wrestling and he is being squashed.

So, to answer your question, IMO it is not worth freaking out over unless the carers are not being proactive and trying to minimise the biting. Biting happens.