@Dark Cloud after modifying the stat line to make it more likely the creature would make the save. If you did that to anyone else, especially during a combat against the creature, they would be livid. And rightfully so.
I didn't do anything to even the odds as that would have reflected negatively on my part, and the roll was simply how it went.
Can we not rule lawyer in a casual game with an obviously lax DM. That'd be nice.