This is a great thread! It really got me thinking and I have no idea what I would do. There is no way I would probably have the time to track down ten cats. The funny thing is the shelter has those window stickers and I have never picked any up! I'm there two nights a week and I don't have any! I will now make this a top priority.
I'm so glad yours was a false alarm but thanks for bringing this to our attention!

btw-For those of you who have a shelter nearby you might want to see if they have those window and door stickers. I know ours sells them for $1 each.