Supercharger pricing discrepancy between vehicles

[Rover8]

I just noticed that one of my vehicles has higher Supercharger pricing from the others (screenshots were taken a minute apart for the same Fremont factory station). Is Tesla testing out different pricing schemes like Amazon was caught doing previously?! The one with higher pricing is a vehicle I have not supercharged before.

 

[GtiMart]

Is the higher priced one a model S/X? Just curious...

 

[Rover8]

Is the higher priced one a model S/X? Just curious...

The higher pricing is a 9mo old MY, I have a 4yr old M3 and 8mo old MX with the lower pricing. The only factor I can think of is that the MY has never used the SC network.