Really need advice on this situation!! 10 pts?

Please let me know if im making a big deal out of this or if I have a right to be upset! Today my husbands ex brought over my stepdaughter, when she was talking to him she pulled out a bag with food in it, she said here make sure only haley gets these snacks!! So I felt offended because we have 4 other kids here and thats not fair to them. It was a bunch of junk food btw. When its snack time they all get the same things equally, so I felt that if she was going bring snacks she should have brought enough for all the kid or not brought anything at all. What I was thinking about doing was putting the bag of junk in the pantery and on sunday when she picks her up put a note saying at our house if one get it they all get it in the bag and handing it back to her. What do you think or how should I approach this?