Do I need to specify that this is a pagan party?

We are throwing a party in a couple weeks to celebrate the spring equinox/Ostara. It's a pagan/wicca thing. I allowed my kids to invite friends and when I sent out the invitation it specifically says what we are celebrating. I feel like if the parents don't know what Ostara is they would just Google it but I gave a brief explanation. My husband is concerned and things we should call the parents to specify that it's pagan so they aren't shocked and go home and tell their parents and then we have angry parents thinking we are trying to brain wash their kids. I don't think I need to call all the parents and specify "Hey! This is pagan!" If someone invited me to Hanukkah I wouldn't expect them to specify it's a Jewish Holiday. If they ask of course I'll go into detail about the Holiday but I don't think we need to call all the parents that RSVP'D and say "Just so you know, this is pagan!"