dude
at the risk of condescending, which i do not want to do at all....
its probably ok because this wasnt a paying client. yeah, they signed a release, but they didnt pay anything.
it sounds like you dont want to use the photos anyway.
soooooo
chalk it up to a learning experience. and if you want to do some more learning, play with those files and see what you get.
sometimes i pull out my ole ist*D and crank it to 3200...during jobs where im making over $100/hr.
or
sometimes i ADD noise to a photo
here is an example
you will be ok...even probably better off. you seem to care about your quality and are eager to get it right.
tip: set your iso warning to 320 or something like that. i do.
(because regardless of the uses of high iso or how much i like them, it is smart to know when to shoot low iso)
good luck, and pm if you want that pic down.
mitch