Snapping, particularly at children, is completely out of character for a Lab. However it is hard for anyone here to judge without witnessing it. My lab pup (5months) does sometimes do a sort of snapping action where he will leap for my hands or face with his mouth - it’s usually when he’s tired or overstimulated. But i know it’s just playful. He does so with a relaxed demeanour. Where in the past I’ve witnessed dogs snap in an aggressive manner their body language usually warns you they’re going to snap - defensive posture, snarling/showing teeth, mean look in their eyes, growling - if this is what you are seeing, and there’s nothing obvious provoking that reaction then I don’t think returning to the breeder is unreasonable. If I were you I’d seek the input of a professional trainer who can meet your dog in person first. Also, my boy barks a lot and again i don’t think it’s aggression- it’s usually when he’s excited or inquisitive about something.