Which hatred generator were you using then? It should use the proc coefficient like critical mass, which means you;d see a lot more with say, cinder arrow than spray of teeth.
I use SoT, yes. The issue is using Ball Lightning which triggered the proc continuously in the past, unhindered by an internal cool down. Using it now, in patch 1.0.4, I'm noticing it returning far less disc, the "blue aura" bubble triggering once a second. Maybe I'm just noticing this now or not, but I'm curious to know if it was stealth nerfed in some way.
Hrm, I'm testing with Ball Lightning right now, and it doesn't appear to have an ICD, unless it's per target, but it is extremely streaky. Some shots refill the globe extremely quickly, and then I can go for a very long time without seeming to get anything from night stalker at all. I just wanted to initially rule out something you may have forgotten.