I don't think this "angle" has been mentioned as a possible source of widespread, though still not totally global, flooding.
This came to my mind since I remembered the story in NG along with some nice supporting pics of huge dunes along certain shorelines around the world that can only be explained by huge sudden floods:
From NG:
Scientists have found traces of an asteroid-collision event that they say would have created a giant tsunami that swept around the Earth several times, inundating everything except the mountains 3.5 billion years ago. The coastline of the continents was changed drastically and almost all life on land was exterminated.
....and this is the link to that page
http://news.nationalgeographic.com/n...8_tsunami.html I didn't search this link to see if the interesting dune pics are shown, or if the connection is made to specifically identified impact sites that likely caused those dunes, but those things were in the magazine a couple months ago.
I later added this for my "edit"
If some astute ancient stone age woman noticed some subtle physical clues of these dune structures and noticed that they look like the little sand ripples on the beach caused by small waves and she figured out a huge flood that they did not actually experience or have any record of in language or written or pictures etc may have occured, that could be a scary thought and lead to mythic stories.