Is that a good thing? When do I become cautious? I want a healthy dog. He is free feed Blue and is very active.He is 8 wks old.

He should not be free fed. That's why he is over weight. When you do not limit a dog to how much he eats you can not control how much weight he gains. Feed him what the bag recommends (on the blue bags its cups per DAY not per serving) and divide that between 3 meals.

Don't free feed; it makes housetraining hell. It's also probably why he's starting to look pudgy. Feed him the amount recommended by your vet or on the chart on the back of the food, and make it into 4 or 5 meals a day.

It's possible that he was underweight when you got him, which wouldn't surprise me from a mutt breeder. Puppies that young should be chubby if they're well fed, don't have worms or any medical issues

Pups that young should be pudgy, it's puppy fat. Make sure you are feeding him a high quality, meat based, dog food. Also, put the food out 3 or 4 times per day (since he is so young) and only leave it out for 20 min. Be consistent on the times you put it out and he will learn when to eat and how much to eat. This will also help with house training him