Out spending some quality time with the Mojo HD, furtherest point of the ride from home when dang, the cranks are no longer spinning freely, making a grinding sound once each revolution, seem to be binding on something.
The bolt that fixes the MRP Mini-G2 chain guide to the pivot had come loose, making contact with the back of the chain ring. The only way to get to the bolt is to remove the cranks. I had a multi tool with me but not the little crank bolt tightener/loosener gizmo. Doh! Nothing to do but walk home.
An MTB spaceship downed by one loose bolt.