10 month husky mix that nips at kids

Question
My family and I just bought a 10 month husky mix.He is beautiful and very eager to please us.However he nips and sometime growls at other children that are not part of our family(ours are 4 and 7).There seems to be no reason or cause for this because the kids are not playing or doing anything to him.When we first looked at him he did do this to our children but I thought he was just excited.Once we took him home he was fine with them and doesn't bite.Other children that I have in the home or take him around he is fine and then growls and nips at them in the stomache or face.They are just standing there talking to me as he does this.I get right down in his face and hug him and he never nips at me, so I don't know if this is aggression or play.I have already put in a call to it's previous owner and they are going to take him back,but I really love this dog already and hate to send him back,at the same time I don't want a aggressive dog.any advice?

Answer
He is warning the children, "Don't mess with me." I don't know if he was picked on by children in the past, children can be cruel pulling on ears and poking in the eyes. He isn't what I call aggressive, he doesn't go out of his way to actively search the children out. You might want to keep a bag of treats on hand, something he really likes. When he is around children and he ignores them, or if you say his name and he looks at you treat him. Dog don't think about stuff they just do what they have always done, that works in their mind, that has "kept them safe". This little exercise re-shapes his reaction to children. If you do this enough he will see kids as something good because when they are around he gets good things.  
Any more Questions please ask!
-Michelle B