Why does my Audi A4's engine make a rattling noise at start-up?

I have noticed that my Audi A4 makes a rattling noise when I first start the engine in the morning. It seems to go away after a few minutes of driving. What could be causing this and should I be concerned?

This could be due to a few different reasons. One possibility is that the oil hasn't fully circulated through the engine yet. Another common cause is a faulty timing chain tensioner. It would be best to have a mechanic take a look at it to determine the exact cause and recommend any necessary repairs.