Yes, it grates on me every time I hear "sentient" being or creature in books and on screen. A "sentient creature" is one that can sense -so pretty much every creature is a sentient one. I LIKE the word "sapient" mentioned earlier (by RoboKaren) and I'll start using that immediately to mean "a living, thinking/reasoning, aware being".
Sentience -simply means the ability to sense, process senses, to feel.
Conscious -can mean not-unconscious, in other words awake not-dormant.
Aware -can mean focused or hyper-vigilant, or that superpower we call introspection.
Sapient -showing self-awareness, wisdom, sound judgement (reason)