I think it might be software... After trying the wifi "fix" in this thread multiple times nothing changed. I was trying to think about what could have triggered this behavior, and it might be attributed to me playing around installing new apps last night. It wasn't until this morning when the symptoms showed up. With that thought in my mind I then tried a total reset of the watch and set it up as new, and opted NOT to import compatible apps. I made sure to uninstall all third party watch apps off of my iPhone too (at least the new ones that I had downloaded specifically for the watch).
The watch seems fine again.
Most of what I had been doing up until it started misbehaving was just learning how to use the features, not adding apps.
If I had to guess, I had a bad app that affected the wrist sensor software. I’m going to wait a day to make sure the problem doesn't reappear, then slowly start adding apps back again. Most of the third party stuff I've downloaded so far has been extremely slow and buggy anyways so I won't miss it in the short term. Hopefully things get better once the ecosystem is more mature.
If it is of any interest, the apps I had installed before resetting my watch were as follows:
find near me, inflation calculator, chaos control, wristmaze, rules!, citymapper, Amazon, chipotle, 8tracks, things, Evernote, yahoo weather, endomondo, weather underground, strava, one drive, yelp, trip advisor, myfitnesspal, withings healthmate, Instagram, Twitter, (among possible others I have forgotten about)