Too early to panic. the low SG would be from stratification more than any actual sulfation, where they didn't get deep cycled much to keep them stirred.
I get the same thing when on solar---the batts don't get low enough to do a proper deep cycle and SG gradually sinks even though the solar is doing ok by its thinking.
I still need to do an over-charge on the batts once a month even when on solar or SG never gets up to tippy top as new.
The over-charge and its bubbling should get it done, but I like to a real deep discharge to 50% also. I am unclear how that compares with just getting an over-charge going for actual amount of stirring.
Sounds like you need a calendar with a place by each date to write down things and then fill in your battery schedule ahead of time. then all you need to do is remember to use the calendar :)
