I don't think you are overreacting - I would hate it if she kept bringing it up!

I agree with chocoholic - you have identified the situations where your baby is likely to bite so at least you can do something proactively about it. If you don't feel comfortable saying something to the other mum, maybe get down on the floor next to where the babies are playing and if the other baby just give some positive play directions to both of them followed up by lots of prasie for good behaviour choices.

If the other baby starts yelling in your baby's face you can say 'we need to use quiet inside voices' or taking her toys 'we need to share the toys' etc ... just point out the behaviour that you want them to do. Make sure you follow it up with lots of praise 'What a lovely quiet voice, I really like the way you are talking to each other!'

It might be an idea to sit and play with them from before problems arise so you have plenty of opportunity to give positives to both of them before you have to start positive re-direction.

Sounds to me like your are handling your baby's biting just fine. That is exactly what I do with my kids. Most kids go through a biting stage. My DD2 is 2 and a half and has only started biting in the last couple of weeks - NOT FUN! I thought I was lucky and had escaped dealing with that issue but apparently not. Her biting has in turn brought out the biting stage in DS and they have bruises in the shape of each others teeth marks on their bodies. It is terrible! They are SLOWLY getting the point though. Everything takes time for them to learn at this age, but I am being consistent and vigilent and it is starting to get through.

Good luck with everything.