I changed my strings the other day and the low E string piezo became loose. Now the string is buzzing like crazy. Is this something that needs to be sent back to be fixed?
Check the saddle height. I noticed that saddles' screws likes to loosen up while there's no strings on them.
When the saddle gets too low the string doesn't give enough tension on the piezo element. To check it simply press on the string in place where it lays on the saddle (I use guitar pick to do that) and check if the open string is buzzing. It shouldn't.