Logo is being stretched

You may need to change the header image dimensions in the child theme. The dimensions are set up within the twentyeleven_setup() function:

$custom_header_support = array(
		// The default header text color.
		'default-text-color' => '000',
		// The height and width of our custom header.
		'width' => apply_filters( 'twentyeleven_header_image_width', 1000 ),
		'height' => apply_filters( 'twentyeleven_header_image_height', 288 ),
		// Support flexible heights.
		'flex-height' => true,
		// Random image rotation by default.
		'random-default' => true,
		// Callback for styling the header.
		'wp-head-callback' => 'twentyeleven_header_style',
		// Callback for styling the header preview in the admin.
		'admin-head-callback' => 'twentyeleven_admin_header_style',
		// Callback used to display the header preview in the admin.
		'admin-preview-callback' => 'twentyeleven_admin_header_image',
	);

Within the twentyeleven_setup() function in functions.php