[kbenson]

Many mammals are supposed to be able to recognize the your in other mammal species based on some fairly universal markers (large head to body ratio, larger facial features), and respond differently to younger and older members of a species. Many Dogs are known to have exhibited this behavior, and treat human babies distinctly different (more gently). I think you are correct and it's entirely possible is child-rearing instincts firing in response to other species that resemble their own young closely (other young whales) or superficially (other, smaller marine mammals).