Eating Animal Crackers

You all know the song "animal crackers in my soup" a Shirley Temple favorite. I have always used this diddy with my pre-ballet students. We sing the whole thing with puppets etc.
So, here's the issue...
I have a family that for religious reasons won't let their children accept a treat at the end of class or let me use holiday tunes etc. I'm not exactly sure what religion they practice, but I do my best to honor their requests. They have been long time customers.

This week at class I brought in Animal Crackers, so the kids could eat one and bring some greater understanding to the song. Well, when this child got back to her Mom after class she explained that she had eaten a treat and I could tell from the look on the Mom's face that she was really displeased. I didn't consider it candy or a "treat" it was a teaching lesson, although I did give it at the end of class to avoid the mess. So, I guess it could be considered a treat.

I observed the Mom gently scolding the child in the waiting room and of course quickly turned back into work with the next class as to not to create a scene. (I know, I'm a chicken) I'm considering sending the girl's Mom an email to explain, or should I just let it go? I feel so bad for the child I don't want her not to trust me. Perhaps someone on the post can explain this type of religion and why a little girl can't have a snack?