i have a similar issue with a printed flannel that i used to make a Split Rail. i left it, once it is quilted it isn't as obvious and i made it for practicality. Why don't you ask the Mom what she wants done? it isn't your fault that print isn't straight of grain. Perhaps she'll opt to leave it, perhaps she'll opt to replace it, either way it is her responsibility not yours. your are the instrument of the craft, she is the source of the supplies.