It also constantly recalculates based on driving conditions. For example, a few days ago I drove on the highway most of a charge, then plugged it in for an 80% charge overnight. The GOM read something like 65 miles after charging when I started it the next morning. That morning, I was driving on local roads, 35mph max, and the GOM crept upward and got to 70. In reality I had driven 6 miles, but based on the lower speed limit, it was figuring my range on the fly and increasing it due to recent low speeds.
ahh- I see you note % increased, not GOM. Not use to % as my car doesn't have that. It is strange it increased, maybe regen'd just a little bit to increase % that had barely dropped or something...