It is common for normal children to focus on one or two things for a while, such as learning the jingle in a commercial or eating cereal in some kind of Mickey Mouse bowl. Generally speaking, these temporary fanaticism will eventually pass. Some normal children are naturally unenthusiastic and don't like to be hugged, but that doesn't mean they must be autistic.
Abnormal concentration and apathy are manifestations of autism can be inferred from this passage.