Strangely seeing nginx welcome page on http with letsencrypt

All well with nginx -t... the default config is present under sites-available, with the symlink under sites-enabled (which it should be, correct?). It looks like the stock file to me...

# Default server configuration
#
server {
	listen 80 default_server;
	listen [::]:80 default_server;

	# SSL configuration
	#
	# listen 443 ssl default_server;
	# listen [::]:443 ssl default_server;
	#
	# Self signed certs generated by the ssl-cert package
	# Don't use them in a production server!
	# include snippets/snakeoil.conf;
	#
	# ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # don’t use SSLv3 ref: POODLE
	# ssl_ciphers HIGH:!aNULL:!MD5;
	# ssl_prefer_server_ciphers on;

	root /var/www/html;

	# Add index.php to the list if you are using PHP
	index index.html index.htm index.nginx-debian.html;

	server_name _;

	location / {
		# First attempt to serve request as file, then
		# as directory, then fall back to displaying a 404.
		try_files $uri $uri/ =404;
	}

	# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
	#
	#location ~ \.php$ {
	#	include snippets/fastcgi-php.conf;
	#
	#	# With php5-cgi alone:
	#	fastcgi_pass 127.0.0.1:9000;
	#	# With php5-fpm:
	#	fastcgi_pass unix:/var/run/php5-fpm.sock;
	#}

	# deny access to .htaccess files, if Apache's document root
	# concurs with nginx's one
	#
	#location ~ /\.ht {
	#	deny all;
	#}
}


# Virtual Host configuration for example.com
#
# You can move that to a different file under sites-available/ and symlink that
# to sites-enabled/ to enable it.
#
#server {
#	listen 80;
#	listen [::]:80;
#
#	server_name example.com;
#
#	root /var/www/example.com;
#	index index.html;
#
#	location / {
#		try_files $uri $uri/ =404;
#	}
#}