Dr. Prius question, gen 3 vs. gen 2

Today I ran a Dr. Prius life expectancy test on my mother's 3rd generation Prius. The charging phase did something different than I have seen on our 2007. In the first phase, after charging up the battery just a little, to around 58% (and corresponding pack voltage), it just sat there (showing 17% on the app) and wouldn't go any higher, even though the dashboard display showed current going to the battery. After quite a while (5 minutes?) the app said to release the accelerator, and floor it again. Doing that several more times eventually charged up the battery. Our 2007 just charged up the battery by holding the pedal down, none of this release and floor it again.

The test said it had 57% capacity and was in fair shape. The module voltages were all close, as were the resistance measurements, and the car has had no driving issues or error codes.

So, is this odd charging behavior typical for a gen 3, or does it indicate some issue with this particular car?