Very normal. Any sudden movements or if they see movement from above. It's a natural instinct. Try to move slowly when around 'em so you don't startle her too much. It isn't a big deal though if they do get startled. My big normal male will hiss at me when I try to pick him up if I've woken him and he doesn't know what's going on. She might calm down as she gets older but otherwise there really isn't a way to calm her down. She isn't aggressive at all, simply defensive