I cried because of Su-Shi

Yesterday we went to a small park playing swing, Zoe wanted to play longer, but the weather was quite hot and it was about her lunch time. I asked her "want to buy bread or Su-shi? " She choose Su-shi. For preventing her from being attempted by the playground, we walked into a quiet lane where can access to the back door of Zoe's daycare. I saw a strange guy and decided to have a short-cut through the daycare to another main road. On the way to the daycare's front door, Zoe's favourite carer saw Zoe and was approaching her expecting Zoe's smile. But Zoe just brusted into crying and ran away from her. Zoe's carer was surprised by her response, but quickly found a positive explanation for Zoe's strange response, commenting Zoe is really smart knowing that today is not her day at daycare.
In the afternoon, when we had great fun playing and singing, I asked Zoe why she cried when she saw her favorite carer. She was a bit embarrased and saying in a very quiet voice :Su-shi. I said "You cried, because mummy promised you to buy Su-shi, but you thought mummy was going to leave you at daycare? " She nodded her head. (don't know how much does she understand).
This morning when we arrived daycare, I invitied Zoe to explain to the carer what happend yesterday, why did she cry when she saw her. Zoe looked at her and said "Su-shi"!