I don't have an iphone to test (only the emulator) but it looks like the inline height you have in the anchor inside the h1 is not being applied.
Try giving the height in the css in the media query for that log at the small width and see if it makes a difference. There's too much code for me to build a local demo to test I'm afraid.
<a class="brand" style="background: url('/templates/strapped/images/logo.png') no-repeat; width:327px; height:95px;" href="/"> Helps On The Way</a>
I don't know if it will make any difference but worth a try.
Ralph's post also reminded me that webkit has a problem with scaling background images so you could also try -webkit-background-size:100%; in that inline style.