I saw this post a few days ago and went scouring my events to see if there was a Cam Plus trigger for any 12 seconds videos despite having cam plus. Thinking, that any 12 second video may trigger the Cam Plus notification for upgrade… I had no 12 second videos 
Not saying it is an issue, and I agree nothing to worry about, but I actually bookmarked the above to share the same sentiment as @carverofchoice. Nothing to worry about.