"Look at" but doesn't "See" summer

Yesterday, Zoe was very excited to take her rabbit to daycare and as soon as we arrived, she showed her rabbit to Julia, one of her favorite carer, and then after talking to Julia, we saw Summer. The most strange thing happened!! Zoe refused to show Summer, another Zoe's favourite carer, her rabbit and refused her hugs. Zoe even cried and hid behind Wayne.
No matter what did I say, Zoe just didn't want to get closer to Summer. Zoe only quickly check when I said Summer was going to cry.
In the afternoon, we went to pick up Zoe and we took her back to the younger group to see Summmer and Julia wanting to find out what was going on. Summer was standing just in front of Zoe, Zoe looked over her as if no one was in the front! Summer tried to hold Zoe's face so Zoe couldn't really look away, Zoe still managed to look at somewhere as if no one was there.
Initially, we thought Zoe probably was a bit angry at Summer because she used to attach to her in such a great level that she might think she was abandoned by Summer. But Zoe has been attended the older group for couple of months. Summer tried to tie her hair up with one hand, thinking maybe it is because of she changed her hair style. Then Zoe finally looked at her!