Hand Behind Head

Earlier today, I was walking past one of my best friends' house. He was standing at the window pulling the finger at me (being his usual self) when I saw a hand from behind his head and it looked like it was about to grab or slap his face. I turned away at this point and quickly walked away, as I was pulling the finger back at him. I thought it was his mother's hand, so I didn't want her to see me. Then I texted him, asking who slapped him, to his confused reply telling me there was no one in the kitchen where he was.

At this point we both got creeped out, and now that I think about it, the hand was like a shadow in a way, quite dark. I just assumed that was the lighting. My friend has been going through some rough times of late, and I was wondering if that has anything to do with it, but what I really want to know is what did I see? And does it mean something?

Then when I finally got home a few minutes later, I went into my room, and heard what sounded like my older brother yelling my name from his room. So I went down the hall to see that he was not home, and nobody else was inside. So I went outside and asked my mother if she had called for me, which she had not, and all I got was a confused and rather creeped out stare from her (she's Catholic and hates hearing bout my experience).

These both happened within five minutes, but in two completely different streets. Are they connected? Is it something trying to warn me or him? Has anyone else experienced something similar? Because I kind of feel like the hand I saw was symbolising something. Please help me.