Puppies this small don't have teeth to keep the tongue in the mouth, so it's common to see them sticking their tongue out a little. However, this does seem to be out a little more than normal, which may indicate that he has an overly large tongue for his snout. I wouldn't worry too much about this right now unless he is having difficulty suckling or other issues. It's definitely possible that it won't stick out as much as he ages.
You can have the vet evaluate him better when you take him in for his first vaccines around 6-8 weeks of age.