iOS WebView doesn't resize Width on device rotation.

When I drop a WebView into a view, I'm having an issue whereby when I rotate the device, the WebView stays the same width as it was initially.

note: I always start out vertical, so rotating horizontal shows a narrow WebView

        var webView = new WebView
        {
            Source = new HtmlWebViewSource { Html = segment.ContentHtml },
            VerticalOptions = LayoutOptions.FillAndExpand,
            HorizontalOptions = LayoutOptions.FillAndExpand,
            HeightRequest = 250
        };

Is this a bug?