Chemicals on the grass!

I met Daddy and Michael at a park this evening. Michael came out to meet me and immediately wanted me to chase him. However, he stopped dead at the edge of the grass and told me to stop. You can't go there because there's chemicals on the grass, he told me. I was impressed, so I asked him if he could read the sign. He told me he could, but I'm certain someone told him what the sign said and therefore he equated that with "reading" the sign. What he didn't understand was that the date listed was for yesterday morning, so eventually he believed me that the grass was safe to walk on and wanted a picture with the sign he could "read."