Sounds like doggone good service to me! I'd do what you just did: Reload and go again.
Our first coach had paired 12V batteries. Always losing one or the other. Went to a single 12V and that was better for us non-boondockers. Had an old Magnetek Converter/Charger that boiled batteries.
Coach we have now (signature) has space for only one and it's 12V, but the IOTA Converter/Charger keeps it charged OK but gently. We're up to 3-5 years on a WalMart RV/Boat/Deep Cycle.
So, sounds to me like you've got a good Converter/Charger, and you pay attention to your batteries. Good on YOU!