mazda 3 wont shift in auto "D" but will shift in manual
 

2006 mazda 3 2.3 Felt the engine seize "drop" (?) and stopped immediatly. 10 min later started up no issues. Tranny shop couldnt duplicate the issue and no evidence of metal debries was in the fluids or engine. They still flushed it. Two days later it stopped shifting. It still runs and will still shift in manuel. Has anyone had a similer issue that in fact did turn out to be that the cars tranny was on its way to not working at all? Will i dage the car more if i drive it as is... My thought is it would still need a new tranny. IDK... Any ideas on how long that will continue to work and or could it be something more minor? It was not talen back to the shop after it stopped shifting in manuel. My delema is should i bother putting a new tranny in. Ok ill stop rambling. Any thoughts or info will help. This is a copy of a thread in another forum sorry for the repeat.