I've tried rebooting and toggling vibration in settings. I've downloaded vibration tester apps from the Play Store. I only have the same ~70 or so apps that most of us use (dropbox, weather channel etc) and I don't run any obscure apps (less than 1000's of downloads), and I hadn't downloaded anything new for hours before the problem started.
I feel I've tried all the basic stuff, except factory reset, I don't think there's anything too obvious I'm overlooking.
So that leaves me facing either a hardware or software problem. I doubt its a problem with the physical vibration motor. Factory defects are so ridiculously rare that it should never be your first course of action. However, if it's a problem with the hardware I could try my local ATT Service Center. If it's a software problem, which seems much more likely, I could try a factory reset on the device. However it seemed a wise idea to post this question to the pros before I go down that road.
Appreciate any help you guys can offer.
AT&T Moto X