Site identifier vs feeder_id

Creating another new system for North Mexico. On a brand new Pi 3 and piaware 3.5 I have:

From my stat page:
Site identifier: b8:27:eb:ce:ec:fc <---- MAC

From /var/cache/piaware/feeder_id:
3f7df80f-d486-4cfa-8a1a-0a160d2280c9

I thought/read they are supposed to be the same, with no more MAC address used. Am I missing something?

Thanks

Alex

That MAC address first connected on March 18 and so is working under the old method which identifies feeders by MAC address (the cutover was on the 20th)