Here's an example to illustrate what I'm asking.

I've been on and off with this girl for a while. We're sort of on at the moment. The other night, she texted: "I almost stopped by your house on my way home to jump you." Clear IOI. I waited 30min or so and replied "Assertive. I like it". She then followed up with a comment about a conversation we had earlier that day: "We just stood outside and chatted about all this stuff". I chose not to reply. The next day she was a little cold -- clearly bothered by my lack of a reply.

So: Am I supposed to cave here and give more attention? Did I screw up by not giving her attention after a clear IOI? More generally, is it ALWAYS okay to be a little distant, or is there a point at which it becomes detrimental?

Thanks in advance!