Why do I get a feeling on my forehead as if someone is touching it during meditation? I do meditate sometimes,not everyday. 

After 5 to 10 minutes during meditation I start getting a feeling  on my forehead as if someone is touching in it.

Sometimes after listening to binaural waves or do yoga, I get this same feeling.

I understand that something is happening to the pineal gland.But my friends who meditate they don't get this, its only me.

What exactly happens here and how does it work? Can someone explain?
Due to ones past store of conditioning one gets different experiences. The main thing is not to attach too much importance to these experiences as thinking about it will be a distraction main task at hand which is the meditation and also perhaps a source of attachment or aversion on how you react to it which is also decremental to meditation.