If I'm deploying a site across multiple servers (to be load balanced), it seems that on one of the servers, the minified assets aren't in assets/cache. It's there in the other ones, but not this one. Is that a database thing that PyroCMS uses to check which asset file to use?
PyroCMS will not check the database for cached assets, that would be weird. It just caches them whenever they are requested. Maybe traffic isn't getting to your other machine?