I did control pickup in that area and I think I may have encountered the same snake. Still coiled up, although when I passed by a few steps uphill it started moving away and I got a good look at its rattle to pretty definitely confirm the species.
I think that might be the first time I've for sure seen a venomous snake while orienteering (more about my lacunae in herpetology than the lack of sightings, probably).