yes it could be a stage they are going thru.
there is this less known or not really talked about what i call preadolescent stage around 5 or 6 years old when for a period its not just tantrums but more. v. hormonal. moody. frustrated. accusatory. a complete different person than they normally are.
my v. intense 7 year old still throws intense tantrums. only difference she knows not to hit me.
also though i have noticed - lack of sleep, hunger, lack of exercise also makes her worse.