Even when people are only joking, Cade has trouble seeing it that way. When there's less of an 'only', he sees straight to the point behind it, and in this case, it takes the rest of the wind out of his sails. He has no excuses to make, but luckily Alistair chimes in before he can.
Cade looks at him warily, his expression withdrawn and his mood verging on hopeless. He's certain this will be the death knell for any rapport they have, or once had.
"..no, I don't think so," he says quietly, giving a small shake of his head and looking at the floor. No, he's just insane. That's definitely better.