Dean, unknowingly, was thinking the same thing as has brother. Trying to get there before they did something stupid. He had been very tempted to tell Buffy to sit tight. However, he wasn't stupid enough to say that to a woman who could break him three different ways, with her pointer finger alone. "Just get here." Was all Dean said. Because hungry. Right. He wasn't sure if he believed that. Truth was he didn't. "The sooner the two of you show up, the sooner we can hit the road." He just wasn't in the mood for Sam's bs excuses at the moment.