Just got off the phone with SMS, they confirmed that seat change was based on reconfiguration due to elimination of the aft BE cabin. Seems that the computer automatically reassigned the seats based on cabin location (i.e seats in the same spot as previous seats). New exit row on 763 is row 20, and there supposedly is not a second exit row. If that is the case, then row 20 will recline since there will not be an exit row behind it. I'll check the seat map on Delta.com and see if it agrees.