I would ask to have it done regardless. You may never get to the truth of it. Who can remember what form the bishop used (they like to play with this one)?, and for a while they were using doubtful substitute oils instead of olive oil. Given that these are pervasive practices in the Novus Ordo, this rises to the level of positive doubt, and I would get it done regardless. What are you going to do, interview witnesses who can testify to the exact form used by the Bishop ... and contact the diocese to make sure they were only using Olive Oil?