With carvana and other online car resellers, they can get your vin just by inputting your plate, maybe whomever the op is buying the tune from is doing the reverse and inputting the vin to find out what state it is registered in, and refusing sale to any vehicle in CA.
I still would not volunteer my vin to some newbie with only 5 posts, it may be a scam to get vin's to re-vin stolen vehicles.