Maybe it still had some water inside the hydraulic system and it has slowly worked its way out. You might have gotten all the water out but without taking it apart you can never know for sure. It might just need a few more flushes try having mikeys old lube shop reverse flow it out then look in the old oil for signs of water. Lets just hope if it is water it wasn't trapped behind seals somewhere slowly cavitating its way out into the transmission. What's your thought Tay?