No.

If they are on D2/1 or A travel they do not need to stop in and say anything. They are on their travel benefits, their own "dime". Some grouches might insist that they stop by, but that is just wrong. It's a courtesy to stick your head up front and let them know you're on board. If you are WO and get stuck with the JS, yes you do need to ask if you can sit in the JS. It's the CA's flight deck, he can deny it, but usually there needs to be a valid reason or people start asking questions.

If the pilot does not have pass travel privileges on your metal: YES, they technically must stop by and present ticket, ID, and certs. They are essentially an additional crew member (ACM) and have to prove it. Some people might try to blow this off, but they're essentially begging for a ride. I've seen one guy get booted off the plane (mainline) for failing to stop by the cockpit (he did not work for the carrier/sub).