Ghost Encounter or A Dream?

This happened to me when it was late at night. I was sleeping soundly on my bed with my back facing the ceilig of my room. It was dark as usual and I remember that I was partially awakened by someone. Someone who came into my room that very night. It was a woman with long hair. I think that she was wearing long robe but due to darkness, I couldn't see the colour of the robe. She came near to me and covered me with my blanket. I thought she was my mom but my mom has short hair! After she covered me with blanket, suprisingly she laid a kiss on my shoulder. I felt the kiss and it was so real. The lady went out of my room but I was still looking at her in a state of partial awake. She was standing at the corridor and this time, staring at my sisters' room. I felt asleep after that and the next morning, i asked my mom and my siblings if they happened to come into my room last night. They denied and they claimed that they were not awake at all that night. When I told them the story, my mm told me that it was just a dream but the kiss was so real. Until now, I still cannt figure out what happened that night, probably just a dream, I guess.