It depends on how you feel. If you really want to clear the air or understand why she ghosted, you could send a very casual message. But be prepared for no response or a negative one. She may be watching your stories just out of curiosity and not be interested in talking to you again.
I wouldn't recommend it right away. Since she ghosted you, reaching out might seem pushy. Give her more time and see if she makes a move to contact you first.
No, don't reach out. Her watching your stories might be a way for her to have a one - sided view of your life without the pressure of communication. If you reach out, it could make things more complicated or uncomfortable for both of you. Just let her be for now and focus on yourself.