I have four whites tree frogs in a terrarium. Every night when I feed them all but one comes down from their perching area to eat, except one. He does not come down to eat until morning arrives. He stays asleep until about 7:00 am or so and stays awake for a while then goes back to to his mushroom cliff. He does not look unhealthy, but for some reason is awake at the wrong times. Any reason I should be concerned?