Noticed that at one moment, my Surface Pro 6 says that there are "3 minutes left till fully charged", then "1 minute until fully charged" becomes "9 minutes until fully charged". Is this normal behavior for the charging estimates? I wonder what would throw this off and cause the time to go up if the device is plugged in and idle (not powered off, just idle). I'm not even on a docking station or connected to any Bluetooth devices. Just the detachable keyboard is connected and that's it. Curious if anyone else is experiencing this with their Surface Pro 6 (….or older Surface Pro..).