Jo considered the offer. It could be a very good thing to have someone to teach Maxine, but if it wasn't the right someone... not that she thought that Sam was wrong, but it was going to be a lot harder to hide Maxine's abilities from Dean if Sam was training her. Not to mention that she wasn't sure what the right way to approach Maxine about this would be.
"I need to talk to Wash about it, but thanks for the offer Sam. I'll let you know."
When Sam seemed to nod his assent to that, Jo pulled the taller of the two Winchester brothers into a quick hug.
"And thanks."
She didn't bother to specify the reason for the gratitude. She appreciated his understanding, his patience, his lack of getting angry over the fact that he'd spent the entire day as a dog, and his agreement to keep this from Dean for now. This could have gone much worse and she knew that Sam was giving her a lot more leeway than he might for someone else. It meant a lot, and she just hoped that he realized that.