I think the suggestion was to use the sans-serif for the heading. This makes sense because you're not writing "Today" — that's part of the interface. Same as you're not writing "May 2012" on the calendar.
The large, handwriting typeface works well for the list items as it makes you focus on it, but the "Today" heading should be different if only to clearly separate the middle section as your "list". Overall terrific design though.
