Just bought 2 leopard geckos. One is older, not sure of sex yet, and the other is a baby, and cannot tell the sex. The baby is very aggressive towards me. And when the other, older gecko gets near the baby or under her, she (?) raises up on her legs and lifts her tail. The older gecko will pause, then will go in a different direction. Does this behavior help say what gender the baby is? Is this behavior normal?