ADAS1000 TESTTONE - leveling First values

Pardon my noob question, I'm starting to play with this and I'm trying to understand. My background is systems, not electronics, so my point is more on the data side of things but still relevant to original post: 

AFAIK, example 4 of the DS activates the testtone with 1mv pp @ 150Hz on all 5 channels, and it "rides" on VCM_REF of 1.3V, while ADC full scale with GAIN0 should be 0..2xVREF/GAIN, VREF being 1.8V and GAIN 1.4, that would be ~2.57V full scale.

I'm getting 0.9mv (marginally ok) range centered @ 1.263V (not at spec) in all channels.

(e.g. Integer values min 8241232 max 8248171)

Would that be considered ok or am I missing something ?

BTW, I also saw that pronunciated "leveling" first values descending from ~1.3V but I guess this is normal ?

edited subject title for duplication
[edited by: lallison at 6:34 PM (GMT -4) on 8 Apr 2021]