Classic Award combined with paid booking

[sat]

Looking at booking a return trip MEL-DFW and using classic point in one direction. The classic point booking by itself is 56,000 points per person economy. If combining with a paid booking it is showing at 72,000 points per person. Am I missing something where by the classic award point required are higher when combined with a paid booking on the other leg.

 

[medhead]

Strange. Sure it's not points plus pay?

 

[sat]

Definitely a Classic Award.

 

[JohnK]

Is it somehow treating the paid booking as a one-way and adding a points cost to the classic award?