Has he ever discussed this? He must have a cast of thousands across all his novels and short stories including characters that only have small roles or are just mentioned. All the surnames can't just be based on names he's heard can they?
Other authors come up with names that sound preposterous (Dean Koontz springs to mind) - does he have a phone book and a book of baby names on his desk?
I tried writing scripts for a few years and could easily waste half an hour trying to find a character name that sounded right (I AM easily distracted though)