What's up with knots and fuzzy yarn?

[tokmom]

I finally bought some Noro Kureyon. The yarn that has been taking over my dreams for a few months. I love the colors. So gorgeous and vibrant.
What I'm finding though are knots where the colors are joined and I'm knitting along and the yarn will go from thin to fuzzy. Is this normal? I will be felting it, so none of the knots and difference in thickness will show, but for how expensive it is (for me anyway!) I'd expect better quality.