I bought a 2018 Outback Premium last week. Excited about it in every way. There is one thing I am curious about though: The TPMS shows that the tire pressure is constantly fluctuating on all four tires. It jumps back and forth between 245 and 260 kPa. Is this normal and affected by the pressure put on the tires while driving or is it a possible issue? Has anyone else experienced it. Thanks!