I'm sure you realize this, but to clarify a bit for the parent commenter: Although the URL is encrypted, anyone watching the connections on the network can still tell what IP address you're connecting to and usually be able to infer the domain name from the IP address.

To state it simple terms: HTTPS protects the URL and all the contents of the connection, but does not protect the fact that you're connecting to a particular domain, the duration of the connection, and the volume of data.