Can an interview go too well?

I would have said no to the question " can an interview go too well?" About a week ago. But now I'm not so sure. I applied to a good modest part time graphic position, they liked the portfolio and the interview lasted over 1 1/2 hours, I left feeling that it was a no brainer perfect match for them and me. Yet still not even a word. The only thing I can figure is that it went too well somehow, and that scared them off. I don't really understand it. The only possible other thing is that the temp agency is the problem. I feel like I should make a gesture towards them independently. Seriously that is how well the interview went.