I have a 2009 Honda Insight which I purchased approximately 4 months ago with 19500km on the clock. While driving on the motorway (freeway) at or near the 100km/h speed limit I noticed the car is often charging the hybrid battery while under constant throttle/light-moderate acceleration. Fuel consumption is generally between 48-51mpg or 4.6-4.9l/100km. This is my first hybrid vehicle so I'm not sure if this is typical or I need to get it looked at. Help!