My dad does that. He's from Virginia, like Jefferson was!
Must be an east coast thing..
pouring coffee into a saucer seems to be an old time country habit. Many of the older hard working country men would do that. My grandfather from southern Missouri and his son-in-law from Kentucky did that all the time. I always wondered if it had to do with all the grounds in the coffee. They put the grounds into boiling water and boiled the life out of it...no filters back then LOL
I think it is, or was, a southern thing. I was born and raised in FL before it was transformed into a giant retirement home for yankee retirees. Many of the adults I knew as a kid cooled their coffee in the saucer. Some, like my grand-dad, blew on it to cool it and then poured it back into the cup to let it mix with the hot coffee that was still there. Others simply blew on it a few times and then sipped from the edge of the saucer.
That was in the days long before automatic coffee makers so the coffee was perked on the stove and was boiling hot. With automatic coffee makers today the coffee is not too hot to drink as soon as it's poured, so the old custom seems to have died out even among the older folks down here.