The warnings have come up again this morning -- even though they came up only once yesterday. This time, the warning didn't come up when I clicked my bookmark. But once they started, they came up each time I clicked a link on the site (such as clicking Go Advanced).
I hope they have stopped. And I hope there is a way to contact Norton and ask, "What in the world?"
I attached a screencap.
ETA: And now they have stopped.
ETA: Submitted a false positive report on the Norton site.