When you originaly changed it did you drain the TC and flush the lines. Otherwise, you only changed aboot 30 percent of your fluid. This might account for it turning color so quickly. I would give it a flush as a preventative measure.
does the AOD have a drian plug? If not I doubt it was fully changed... the shop didn't even know about the AODE plug so they wouldnt have even done that unless I told them! Thanks, I think you figured it out!
There is no drain plug for the transmission. You have to drop the pan. However there is a drain plug for the torque converter. On the bottom of the aluminium bellhousing you will see a rubber gromet. Remove it then spin the engine until you line up the tc drain plug. I think it's a 11 or 12 mm plug. The tc will take a long time to drain. Make sure you use a fluid that meets the mercon v specification.
Also make sure you do not discard the pan gasket. It is reusable! Those cork gaskets suck. I found out the hard way!