Dreaming of wearing a mask is often a dream of how you want others to see you. A twist on this theme is that you may be afraid others are perceiving you without knowing the real you. It may be that the mask attaches and removes from your face, depending on whose company you are in. Also, others may be conspicuously placing the mask on you to give you an identity that you are uncomfortable assuming. Or, they are wearing the mask themselves to deceive, frighten, or amuse you.
If you are wearing a mask, who is in your presence and what is the mask like? Ask the same questions if others have the mask.