If we are talking about an Auto, the most likely culprit would be someone filling with, or topping off, with the incorrect Automatic Transmission fluid. It's also possible that someone put another fluid than AT completely.
I would guess the same for cause for the brake line. Someone under your hood not paying attention to which fluid was getting added to which system.
Have you had had your oil changed by one of those drive thru places, that tops off all you fluids during an oil change?