bq40z50 Overcharge Trip

While trying to run a learning cycle, I got an OverCharge trip, which turned off the Chg FET and halted the charging (gotta turn off Protections for learning cycles!).

What I don't understand is why:

RemainingCapacity() = 4738 mAh
FullChargeCapacity() = 4826 mAh
OC:Threshold = 300 mAh

The definition for an OC Trip is when RemainingCapacity() => FullChargeCapacity() AND internal charge counter => OC:Threshold

Why did it trip?

Thanks.

Tom