Web Lead Form not using correct dates

Web Lead Form not using correct dates

Hi,

I have a form on my site which creates a  lead on my CRM system:

http://www.thesafaricollection.com/contact/

All works fine, except the 'Travel dates to.' field randomly inserts an incorrect date.

The 'from date' seems to work fine, so I know it's working - I am using mm/dd/yyyy.

Any ideas?

thanks

Matt.
(Developer)