The c in cDate is a common naming convention used to identify calculation fields. Is this a calculation field? If so, how is it defined? Is cDate also the field in the header showing the wrong date or is this a different field?
Best guess is that when you are in browse mode the first record of your found set might not be the current record and thus you see a different value in the header than when you print or preview the report. When printed/previewed, fields in the header draw their values from the first record in your found set. In browse mode, it'll be the current record and this could produce a different value in a field in the header if it is not a global field.
Duh! LOL. Thanks Phil.