License

This is something that only a TreeHouse staff member will be able to say for sure, but I'll give a guess. (If you don't receive a reply from a staff member here within 24-48 hours, I'd try emailing them at help@teamtreehouse.com).

I believe as long as you are only using the source code for personal use then there is nothing to worry about. If you are using the portfolio site you created in the course as your personal portfolio (and not changing anything), then you should probably make it clear for any potential viewers of that portfolio how you built the Website (as in, say something along the lines of 'This portfolio Website was created during a course taken on TeamTreeHouse.com'). I would recommend changing it up though anyways, it's good practice and it will make it more unique to you.

P.S. I read the Terms & Conditions page and there doesn't seem to be anything expressily against it but it's also very vague - as these things tend to be.

I would say this, there is no license with how you code something, you can call your own. Now with images, or logo's thats a different story, you would need permission to have someone's logo or image on your site.