The boarding pass in the AF/KL app is different to the one stored in passbook. In passbook it only states "Sky Priority" in red and if you click the i at the bottom, it will show your FF level on the reverse side.

When reseating you i assume the FA would have known your level as well, as she would have used the iPad which would bring up the information.
Don't forget to claim your downgrade compensation (assuming you were downgraded from Business to Economy Comfort - as KLM does not have any premium economy).