I have seen a few posts where it is obvious the person is in denial and asking about justifying their own sobriety date. From what I have seen in AA and on here I think the topic of sobriety while smoking pot. My take is this is a recipe for disaster as the definition of sobriety is not being in an altered state from a substance.
I would ask why you are doubting and why this might bother you. Do you see your sobriety as a contest? If so, I don't think the motives are true or healthy.