I've noticed that during the course of the day, the battery meter for the HV battery will change often. It frequently drains to two ticks and then charges back up to near full while driving. Ordinarily, I wouldn't think twice about it, but the battery meter in my parents 2nd gen rarely drains past a few ticks. Is the battery meter behavior different between the 2nd and 3rd gen?
Any chance you are running the AC in stop and go traffic? The HV battery will drain quickly in this situation. That is about the only time mine will drop to 2 bars and then charge back up.