I have had my share of mishaps.
I think more information is needed to isolate the problem.
Did you shut the water off? Did the water leak after having a shower or bath? Did it continue to leak after the shower/bath was over? Was the water warm or cold? How much water? What kind of pipes are they? Is there any individual shut offs? Was the drywall wet on the other side?
Did you inspect the tiles. I rented a crappy place in college and you could have pushed the tiles in as the drywall was just like soggy bread. We had to tape plastic bags over the loose tiles.