If you have that long of a warranty, it only covers the powertrain. Struts are considered a wear item and not covered more than 3yr/36K.
As far as them being loose, the only thing you can check is under the hood on the strut towers to make sure they are tight. If they are, then chances are the strut plate is bad and that is what you hear.
Let me know if you have other questions.
Tuesday, March 28th, 2017 AT 8:04 PM