He was reasonably sober, for one. And he wasn't an emotional mess. He supposed that, daughter or not, he just didn't know Ellen well enough to be ripped apart the way he was when Sam was gone. It still hurt, sure. He was still mad. Irate. But it was different.
He and Mary were on the case, going back through Ellen's room, then Jo's, looking for any clues or similarities they could find. They were in the car, driving to Harry's to take a look there (despite the sleeping vampire) when Dean's cell phone rang.