I found the solution to your problem.
I had faced the same irritating problem where iPhone shows excel date fields as dollar figures on an excel spreadsheet. (I am using Microsoft Excel 2003 SP3 and browsing on iPhone 5 iOS 6.1.3)
Turns out, the fix is pretty simple. You would want to avoid formatting your date as a "Date" format in Excel. Instead, change to a "Custom" format.
Step 1: Go to your spreadsheet in Microsoft Excel
Step 2: Select the date field (or select the entire column/row), then Right Click and select "Format Cells..."
Step 3: Click and change the category type to "Custom" (at the end), and type: dd/mm/yyyy. Click OK.
Your date format will now display correctly in iPhone, eg. 15/03/2013. You can of course, change the display format of the date. I use "dddd, mmmm dd, yyyy", which formats my date to "Friday, January 04, 2013".
Hope that works for you! 🙂
Keith