It's probably because she is responsible for you and it's more imperative that you are protected than anything else, of course she was traumatized, but the drive for self-protection typical of any human being is probably akin to just a small fraction of what that maternal drive towards offspring has behind it, does that make sense? You don't sound like you're processing the event and she is unable to miss the flat affect and indifferent tone as a problem that is going to manifest itself like a timebomb. My guess is she feels like there are signals indicating that residual after effects or some undefined "harm" is incoming, yet can't discern from what direction it's arriving yet, has to protect you but you're numb or have no desire to talk about it, so you don't, hypervigilant ptsd is probably onenof her symptoms from the rape which was exponentially as violating by having subjected you of your experience which my god, she is hurting. I'm so sorry.