sandiego,
For the A, the "other" costs include mainly support items necessary for various base locations, crew training etc., "must haves". The cost goes up in 2017 and then fluctuates in out years based on aircraft quantity produced for the USAF. Most of the F-35s built so far are A models, over 120 of which 20 are dedicated for tests. Few C models have been built and LM isn't that far down the learning curve at this point. I suspect the C airframe cost will decrease (It should) given build experience and quantity.