My experience with T-IV is that it turns into a dark-cranberry like color fairly quickly. There's a RX330 parked outside that received a full 12-qt flush with T-IV about 6,000 miles ago, and the fluid already looks similar to cranberry juice. The fluid is probably just fine.
Also, the pan threads on Toyota transmission pans can be very delicate. I have personally destroyed one of them. When that happens, you end up replacing the trans pan b/c it is difficult to get the plug back out.
I think the torque spec on some of those drain plugs is as low as 14 ft-lbs. Nowadays, I elect to remove the cooler lines and "flush" the unit instead of touching that drain plug.