Update and resolution
After not getting any traction here, I just started keeping a log of the issue on my blog.
RESOLUTION: After subsequent power loss and a diagnostic visit to Scanwest on Greenwood, it was suggested that the ignition coil might be failing. The replacement was within warranty horizon, so I took it to the initial shop that replaced it, Maddy's on Aurora, and they verified the issue and replaced the coil without incident.
No further power issues.