Yes, the color change is normal. I remember my neice crying when she found out my first Yorkie puppy wasn't going to look like that when he grew up
. My Tiah is 5 years old and still changes colors. Cowboy is 2 and is still changing. They say "Yorkies are like a box of chocolates.....". They resemble each other a LOT as pups, but you never know what you'll get as an adult.