You may be right - I have not read the novelization, so I am not sure exactly when Kylo went Judas on Luke (to use a Good Friday analogy).
But, if Kylo is ~ 30 yrs old in TFA, and Rey is ~ 19 yo, Kylo would have been ~18 when Rey was 7... the perfect age for an adolescent male to throw a tantrum! :-P
Is there evidence I am missing that demonstrates that Kylo turned about six years prior to TFA?
The novel "Bloodlines" is set six years before the Force Awakens and it is said that Ben is out with Luke looking for old Jedi Temples.