I'll start by saying DD is not my PFB - but I am super-protective and all my kids might as well be my PFBs
.....not sure if i am thinking straight here!
DD is 3 - started nursery in jan.
When dh was getting her changed for bed called me to show me a mark was at the top of her arm - it was a bite-mark 
he asked her about it and she said X bit me in the playground....another 3 yr old in her class. she said teacher took me in for a snack, and made X say sorry.
She told me the same story when i asked her about it. I dressed her in her uniform at lunchtime and there was no mark....it is fresh and most definitely a bite-mark from another child (she cant reach the top of her arm with her own mouth).
We have taken pictures of the bite-mark.
I overheard teacher telling X's mum last week that he had been biting.
AIBU to think the teacher should have told me when i collected her from nursery that she had been bitten today?
I think i should speak to her tomorrow and show her the pictures - the mark is quite bad! but is that a bit OTT?