How often does you NB eat?
A 5 hour stretch of sleep now and then isn't uncommon when they're in a sleepy part of a growth spurt. Otherwise, 1-2 hours apart usually for mine. 3 can be normal for some if they're nursing really effectively. Count wet and poopy diapers, if he has plenty and is gaining weight he is fine, if it's a little less than it should be, try and wake to feed.