so a small update after a week. i noticed this happened once more on a 60 mile drive at around 90% charge (at this point regen is fully functional usually), where regen in B mode was the same as D mode,, but the problem corrected itself later on in the drive around 60% battery charge remaining.
Today i noticed a different symptom, D and B modes behaved normally so i got more regen in B mode than D mode, but when i would use actual brakes, it would not add any extra regen, no matter the speed at which i do it (25+ mph braking always adds regen to max it out but it was not doing it today, it only scaled the regen as if i had my foot off the brake when i was coming to a stop).
wierd stuff.. i scanned the car again after clearing the codes last weekend:
is stuff like this covered under the warranty? i am not sure i feel like paying to have this fixed but my car was first registered 12/2013 so it is a very late 2013 model. (mfg 11/13). it even has a 2014 paint code (tri coat pearl white).
I assume I have the original 12v battery so it could be that it is slowly dying, though the car sees the charger every day and has the solar panel which sees sun most days.
Edit: quick look through user manual says replace VCM and then replace PDM after some diagnostic, didn't dig too much further into it but sounds like expensive dealer only replaceable stuff (vehicle control module or power delivery module).