Check the level after any service on the inverter coolant loop.

In servicing the inverter/transaxle coolant loop on mine, dealer service techs are now 0 for 3 in getting all the air out. In each case they supposedly used the fancy-schmancy flush-and-fill tool. The first time I took it back. The second I asked them to comp me a bottle of SLLC and they were happy to oblige.

It's easy to check it yourself, so do that before driving at high speed or more than a few miles in hot weather.