Ok, it's a cane creek headset—I don't know which model—and I'm currently on their website trying to figure things out. Will let you know how it goes (after work today).
I have a strong suspicion that something is just installed slightly wrong, although that might just be the optimist in me. When I got the bike, the headset/fork was secured with a zip tie, so I imagine it wouldn't have been hard for something to get in the wrong place (or get put in upside down) somewhere between the previous owner breaking it down and me building it up.
Really hoping this isn't a bike shop issue. Just threw down a bunch of money on parts for this bike—not really worth it if it still needs work.