Paste the following code in the Javascripts section of your page selecting 'Before Body End Tag' as the placement:
<script>
$(function(){
$(".lp-form-errors").click(function(){
$(".lp-form-errors").fadeOut()
});
$('.lp-pom-form .lp-pom-button').click(function(){
//Change the time it takes for the error message to dissapear here (the time is in milliseconds)
setTimeout(function(){$(".lp-form-errors").fadeOut()},6000)
})
});
</script>