thanks Michbolt. The warning light (and therefore code?) stayed off during the 1hr drive home from dealer. If it stays off during tomorrows driving, I'll ask dealer of absence of warning light means 'no problem,'.I would defer to the service tech, but there have been a few reports of a relay error due to timing issues (not an actual failure). In those situations, just clearing the code resolved the issue (the code didn't come back). In your case, if the code persists, then you probably have to get it repaired.
Have you had your battery replaced under the recall? Are there any outstanding recalls on your Bolt (software updates)? Another possible (cheaper) option is just to have the software updated (if there are any open recalls) and see if that fixes the problem.
Drive battery HAS been replaced, and all known software updates completed. (surely there are no UNknown updates).