I don't gloat at your misfortune.
edit: It may be that high spawn rates are needed, I'm just used to what I know. Sorry If I seem like a prick.
There's many things to consider here.
It's rather safe to assume the spawn rate has been nerfed. A blue commented on it, and from the looks of his edit one can assume the nerf was intentional, but the devs are working on how to spin the justification at the moment.
Your experience seems unchanged, but you also admitted you haven't really been herbing it up since launch. First of all, you're probably aware that spawn rates are influenced by zone population. When MoP launched, nodes were respawning immediately because the zones were jam-packed with warm bodies, and Blizz wanted to ensure there was enough for everyone.
While the spawn rate was still considerably good, it wasn't been the way it was that first week. Yeah, that was crazy, but there was a crazy amount of people in the zone, so there was a reason.
As for another reason you might not be seeing a difference, there's a decent chance you're the only one out there gathering at the moment. Many gatherers I know aren't bothering for the time being, in hopes that this is simply a bug.
You also have to take into account your sample size. You gathered for only a few minutes. That's not really enough evidence to make any conclusions. On Tuesday, one of my alts logged in right on top of a rare quality Giraffe Calf, but it wouldn't be accurate for me to say southern barrens is swarming with Giraffe Calves that are all rare quality.