I've only recently got around to setting-up proper Default settings for new tasks, and have encountered a problem when creating a new task via my browser (not sure whether problem exists on iPhone sorry).
One of the Defaults is the Start Date which I have as "Today", but I note that quite often (not always) the date inserted is yesterday's date.
Is this a time-zone related problem?
EDIT: Sorry - all above references to Start Date should read Due Date. Apologies
This could also happen if you leave your browser open over night and add a task the next day without refreshing the page. The page will still think that it is yesterday because it hasn't refreshed yet.