How could a person have "liked" a Facebook post if they hadn't even gotten into Facebook yet today?

I posted a short story, and it showed that my daughter and one other person “liked” it. My daughter called a few minutes later and I made a comment about the post.
She said, “I haven’t seen it. I haven’t checked my Facebook yet today.”

…..Could her account be hacked? Is this something she should notify FB about?