I have been researching Victron's "rebulk voltage" terminology and actually found more than i expected.
There was a firmware change (i am running 1.46):
>
Solar Charger firmware: v1.42 / v1.43 for all BlueSolar- and SmartSolar models
...
And the re-bulk voltage has been lowered from 13.7V to 13.4V (for all battery types).
>
Epiphany! (with the help of enough info: rebulk 3.35v)
I never actually get to down to my "hold at float" voltage of 3.3v because the rebulk is .05v above that. THIS would explain what I am seeing: entering a rebulk full charge cycle (just a smidgen above my float value).
This is a relief because i really trust gnubie's knowledge and experience. Thanks for prompting me to dig deeper!
I learned something today!
(thats 2 in one day, thanks to smoothJoey via a different thread)