The date format mm/dd/yy is localized by Excel: even though the file specifies a different format (e.g. dd/mm/yyyy), it will be drawn differently based on system settings. It makes sense when the producer and consumer of files are in the same locale, but that is not always the case over the Internet (like in this case). Unfortunately there is no “smart” way around this yet.
To get a correctly formatted date in the generated PDF file, you can save the date as “Text” format instead of “Date” format. This way the date will always be printed as you can see it in your Excel file.