Today I downloaded the latest Santana song off of Itunes on my ipod touch. Everything went smoothly until later this night when I went back to listen to it. It was gone, no trace of it even in my itunes downloads section. Unfortuntely, I didn't have time to sync it to my pc. I know I paid for it, since it prompted me for my itunes account password, and I listened to it all afternoon. What happened?