Yeah, I think her concern is the whole texting 'game'. I've heard of this before, but I never really paid it any mind.
The texting 'game' is a game of flirtation, apparently, when the two parties involved try to avoid texting as much as possible without having the other party lose interest.
So if you respond too quickly or with too much information, you can be seen as too eager.
I never understood, so I just texted people at my own pace. That means the window between two texts can range anywhere between one second and a year. I think that most INTPs either a) don't understand the game or b) never cared to play, so your INTP guy probably didn't mean anything by the delayed time range.
He probably did think of you, but was too shy to text. Or in the worst case scenario, he kept procrastinating on texting you back.