My automatic transmission shuddered and then stopped after decelerating, is it the transmission?

My automatic transmission shuddered and then stopped after decelerating slowly at 40mph, is it the transmission? I re-started the car then tried putting it back in drive but it did the same thing, I checked all the fluids, the transmission fluid looks fine and everything is topped off... The car seems to be running fine now, but I don't want to risk the same happening.|||well if it is really cold you may be having a problem getting enough fuel to the engine. Permanent fix would be to replace the fuel pump or filter simple fix would be to add fuel preservative with antifreeze to every tank.