Once a project is open to the public, that doesn't mean it's set in stone. Things change -- dates, requirements, plans, funding. Questions are answered. Addenda are issued.
You'll need to stay up to date and keep an eye out for changes.
To get notifications about a specific project, navigate to the project's main page, and click "Follow." The button text will change to "Following." This will make sure you get notified via email about updates to the project.
To unfollow a project, hover over the button "Following." The text will change to "Unfollow." Click the button, and you will no longer be following the project.