Very minor Invoice emailing issue

Minor bug : If you email an invoice to a customer and then have to change it, you are informed of the Last Sent date. If you have a particularly annoying and pernickety customer (or in this case, wife) who wants it changed AGAIN, then the the 'Last sent' date is the original date and not actually the 'Last sent' date.
Like I said a very minor point, but I just thought you might like to know about. Don't rush to fix it - i'll just sack the wife.