There are 8 bars total in the battyer level display. If you have 7 to 8 bars the entire graph goes green. If you are between 3 and 6 bars the graph is blue. If you are between 1 and 2 bars the graph goes red.
Do not worry or be concerned about your battery, ever! The vehicle takes care of the battery. It will never get undercharged or overcharged.
Consider, if you had a full 8 bars and it was green the battery would be no more than 80% of capacity. Now, if the graph were empty and you had no bars the battery would be 40% of capacity. So, the graph doesn't represent the total battery capacity, it represents the system limts of discharge and charge of the battery.
The color coding is there to allow you a quick reference without having to count bars.
You probably got 7 bars because you were descending down a hill and doing some regenerative braking.
I've seen 8 green bars every day this week, twice a day.
My stepson is at 'Zoo Camp' this week, and the zoo is at the top of a hill. Coming down that hill always makes me end up with 8 green bars. It also lowers my total fuel economy for the day, so my numbers have been steadily going down this week.