Everything sounds like it is just fine. I travel with my OBDII gauge hooked up continuously to monitor important functions that are going on. One of the things I monitor is the charging voltage. During normal operations, Winter or Summer, my charging voltage will swing from 13.5 to 14.5 volts. If I was to pick an average, I would say that would be around 14.2 volts BUT, it never stays at one voltage long enough to call it an average.
By watching the charging voltage fluctuate you get an idea of what the computer controlled charging system is doing. Basically it is compensating immediately for any needed charge to keep the house AND chassis batteries at peak voltage. If your inverter is on, then your house batteries will need charging a little more often than the chassis batteries.
My AGM batteries have endured this charging pattern for about three years with no damage at all. I am guessing that everything is normal and your charging system is operating just fine to keep your batteries at peak charge.
