All of my listings (at least all the ones I looked at) have been opted into international shipping. I do not ship outside the U.S., and had all listings set for domestic (U.S.) only.
Happened to me as well.
I used to offer intl on select shipments, but have since limited shipments to Canada on select shipments because of increasing widespread return abuse. I've shipped 100's of intl in my 20 years on ebay. It's come to this.