using a php script to preload cache

So here’s something interesting I’ve run into:

I set up a simple script to grab urls I’d like W3TC to cache, and set it running. It works great but no cache gets created. I’ve tried file(), get_file_contents() and curl and nothing seems to trigger a caching even, even though I grab the whole page and display it in the browser.

My thought is that perhaps W3TC sees I am on the same server so ignores me, or perhaps it is ignoring requests without certain headers present. I can create any needed headers or user agent spoofing with curl if need be. Does anyone have insights into what I am up against on this?

Thanks for any help!