Sam and Dean didn’t think to tell them where they were going, so at first they might think the boys just went a little farther out in the motel to search for supplies. Eventually, they’ll realize they aren’t coming back, and they’ll go to Dean’s home to search. When they find it abandoned, they’ll be forced to think that the boys were kidnapped or taken away, just like Bree was.
One way or the other, Sam and Dean will have a lot of explaining to do when/if they get back there.
Brothers Apart 