If I cast on 90 stitches with the main color (blue). When the pattern tells me to start knitting with the first contrast color (raspberry), I will have to knit that color onto the needle (like adding a new ball of yarn).
I just answered my own question! A new stitch is not added when you add a new ball, so I'm sure it isn't added when you add the new color!
I just had a "DUH!" moment!!