Was It a Ghost or Was My Mind Playing Games?

From: 
Story type: Ghost
Location: My secondary school Leicester UK
Source: Form Submission

It was in my old secondary school, i must have been about 15, i'm 21 now, my friend and i were walking down our corridor at school, when we were at primary school we had a girl in our class, she was from Iraq, during primary school, the Gulf War broke out, so her and her family had to go back.

This happened to us many years later, we were walking down the corridor, and we were actually thinking about this particular girl. All of a sudden we felt cold, there was no one else around at the time, we both turned our heads and to our surprise, the girl who we had been talking about had walked past us. She turned her head to look at us, and smiled, and carried on walking down the corridor. My friend and i thought that we were seeing things, because soon after that, a few more of our friends who knew her also from primary school, were walking in the corridor, so my friend and i asked them if they had seen this girl, they said that they hadn't seen anything.

We were confused, because both of us had seen her, but nobody else had. Up to today, we still don;t know whether it was an apparition, or whether it was our mind that was playing games on us.