My original factory cd player was doing the same thing. Sometimes it would try and give the cd back after I hit eject, but it wouldn't come out. Then, maybe I'd get it later that day, maybe in a couple days. It was soooooo frustrating!! Listening to the transport click away but producing nothing.
I figured it was only a matter of time before it would eventually not eject the cd at all, and I didn't want to be stuck like that. Just installed an aftermarket unit a couple weekends ago, and have been loving it so far!