Version 1.3.1 Menu issue

Hi,
I have just implemented 1.3.1, and all has gone well, with the exception of the menu.
What I have found is that if I use any font other than open sans the menu flicks between fonts as you hover.
Looking at the CSS, the menu is hardcoded to open sans.
I have had to make the following custom CSS to override this (or of course I could remove the line in CSS that actually hard coded open sans.

.main-navigation ul li:hover > a {
font-family:Arial, Helvetica, sans-serif;
}