Today after the charge it showed 13.10 Volts.......
Yes that would be surface charge, whereby the chemical composition that dictates a fully charged battery had not or could not be absorbed into the thickness of the plates. Think of it as a form of super charging.
It will leave the electrolyte closer to pure acid though which over time will errode the plates. That's why smart chargers drop to a float charge voltage when near full charge is sensed. Some ECU driven alternators with remote regulation offer this as well.
Putting the headlights on for a minute will quickly remove the surface charge.
