He was probably so interested in you that his mind could not handle the extreme exposure and had to dart off to avoid overheating.

I had this happen to me once and got the job, people often have things on their mind I wouldn't count yourself out yet!

Maybe hes thinking of the great future having you on the team....or lets hope so

The manager might just be having an off day? it doesn't mean you didn't get the job, so keep your hopes up!

He was thinking of breasts and oreos.

Some people have ADD (attention deficit disorder)... Even if you don't get this particular job, don't let it rattle your confidence. There will be other opportunities for you, so keep your chin up!

It's reasons like this that I stopped taking interviews held at night during which I'd have to sit above the interviewer, looking down at them.

Keep your chin up op :) It isn't over until it's over. If that interviewee couldn't be bothered to show common courteousy (wether interested or not) then you might've found yourself in a worse position in the job then before. There's a lot of opportunity out there.

Keep your professional stature & dignity no matter what. You never know how far that can carry you

He's probably an INTP and he zoned out.