Is it normal for the top of my dog's snout to smell faintly of moth balls?

I wouldn't think so... perhaps he's found some moth balls somewhere and gotten his little nose into them?

If you think he has gotten into moth balls then you need yo get him to the vet, moth balls are very poisonous to dogs.

If you do not have moth balls in your house then I would still be getting him to the vet anyway to rule out things like a sinus infection.