I don't think what the OP experienced is a hallucination. It could just be memory recall....your nose has a memory as well. Something in the environment can subconsciously trigger the memory and you could feel like your smelling something. As long as you're aware that what you're smelling isn't really there, than your fine. When you start searching around the room for the spaghetti you think you're smelling then it's time to go get some help