Did you recognize the face? Was it a friend looking in to make sure you are ok? Or was it a scary face and you were afraid?
Dreams like this can be frightening if you think the face belongs to an intruder.
Someone watching might be a symbol that you fear others watching what you do and you are insecure. Or that you had a bad experience as a child and this is a memory that comes back.
Assuming the face was on the outside and you are safe on the inside, maybe the next time you just close the drapes and see what happens?
