You should be able to log into apple support and see if there's anything listed there.
https://selfsolve.apple.com/repairstatus/GetRepairListAction.do
If you really didn't send anything in and they're sending you something out of error, please let them know. I dont know if they'd worry about having you return it but I'd hate to find out that mine, or someone else's, replacement is going to the wrong person and making the wait time possibly that much longer.