My husbands ex...

I have been with my husband for 4 years now. He has a daughter from a previous relationship who is 6. Well her mother and I get along great!! We text each other all the time. Hang out at her soccer games, and we are even friends on FB. Well... We were😕 
I don't think I did anything, but I just noticed yesterday that she unfriended me on Facebook. I'm a little heart broken, but feel a little awkward at the same time. I don't think I will bring it up with her. But I can't figure out what I did to make her unfriended me. Should I be worried?