Personally if you don't suspect abuse then leave it alone. You don't know if it was the 40th time dad had said stay in bed and go to sleep!
You know IMO if a lot more people did things the "old" ways the new generation wouldn't be spoiled, have.it.handed.to.me , i.deserve."it"....at titudes!
Now....leaving many bruises or marks etc. THEN I'd place a call for sure.Spanking is one thing...abuse is another.