I just noticed today that my Habanero Prius C 3 has green caps on all the tires where you would refill them. My wheels are the 15 inch steel wheels. Does anyone else have this? Also, does this mean that they are nitrogen-filled? No one at the dealership or the manual says that they are nitrogen-filled, so I don't know if they are. My past car had green caps and it was because they had nitrogen.