Wiggly Piglet and Bouncy Tigger's Playpen

Mckayla gets along with most kids she’s met so far, but for some reason she didn’t like this little girl last last night. We took Mckayla to Gymboree after work. There’s one girl there, about the same age as Mckayla, with her Dad. We’ve seen them almost every time we’ve been there, even on weekends. But we haven’t really met the Dad yet – he wasn’t interested to talk to anyone there, not even a smile or nod to acknowledge anyone. Mckayla was on the rocking boat with another kid, and the little girl walked over and wanted to join them. Mckayla saw her coming and immediately pushed away the little girl’s hand as she tries to get in the boat with them. We stopped her and told that that wasn’t nice. And took her off the boat so the little girl can play. Then, few minutes later, the little girl came over to Mckayla while she was playing with the table with animal magnets. They stood next to each other and played along. Then, all of the sudden, Mckayla turned to the little girl and grabbed her hair! I picked her up again and told her “NO!” and took her to another area of the play gym. Mckayla is usually pretty good with other kids and willing to share her toys with them. I don’t understand why Mckayla doesn’t like that little girl?