On mobile, the tooltip keeps showing once scrolled to the top. It won't go away unless you tap again elsewhere. Fixed JS here:

<script type="text/javascript">
		$(document).ready(function(){
			$(window).scroll(function () {
				if ($(this).scrollTop() > 50) {
					$('#back-to-top').tooltip();
					$('#back-to-top').fadeIn();
				} else {
					$('#back-to-top').fadeOut();
					$('#back-to-top').tooltip('hide');
				}
			});
			// scroll body to 0px on click
			$('#back-to-top').click(function () {
				$('body,html').animate({
					scrollTop: 0
				}, 800);
				return false;
			});
		});
	</script>