Beeping iPod

I was getting ready to go to bed. I have my iPod plugged into my iHome at all times, I rarely ever take it out, usually I do it to update the songs, but anyways, I reach over to turn it on and it makes a weird beeping noise for like 2 seconds then it just works as if nothing is wrong. What could be going wrong, This is a 4g 20gb, and its was replaced December of last year. I hope it isn't dying cause it works fine now.