I've had this happen before when I had an overnight layover. Are you still within 48 hours of completing your trip? If so you can call AC reservations and a lead agent/supervisor can make manual adjustments to your upgrade credits (and they tend to be quite helpful). But after 48 hours IIRC they don't have the ability and you will have to submit a request.
Eupgrades were always based on the ''lesser of'' calculation so the correct amount should be 4. unless you had a stopover, then it would be calculated as a new itinerary.
Last edited by kwflyer; May 27, 2015 at 1:17 pm