I wouldn't even call this bullying yet, at this age, just a child with a lack of social skills acting out
Although some might say that acting out would tend to occur in interactions with various children, therefore form a pattern which in general may be noticed by the teacher. From the OP, it appears the perp's actions may be directed at one child, who may be targeted for the aggression. Additionally the perp may choose his timing so that his aggressions remain covert, characteristic of deceit/manipulation.
