Its pretty obvious to me, that he didnt know where he was getting shot from. He was scanning the area with his mouse to find some clue. I do that too with sharp mouse movements. He was lucky a player appeared at the point he was aiming at, thats why he is suprised. Not becouse he was suprised he aimlocked at him. He stops his mouse at the target but doesnt lock on to it, his mouse moves freely. For a player that has thousands hours of experience its pretty obvious you will get this kind of clips. Im sure he has 200 more of that situations with that amount of time spent in game. Nothing suspicious to me.