Do you think its weird for a best friend of 13 years to do this?

I asked my friend of 13 years if she was going to have a birthday party for her daughter. She didn't even answer me when I asked.
I found out yesterday on facebook from one of her friends saying "thanks for inviting me I had so much fun and lots of laughs over pizza."

It was almost like she was trying to hide it because she didn't even post photos on her facebook.

I didn't do anything wrong to her at all. But she's treating me like I am not even really her friend.

My plan is to go ghost her after December because we had a plan to go somewhere and I bought a costume for it! So I'm going. Is that a little childish of me? Maybe. But I'm done with being treated like that.