Was it raining?
Some put an unplugged iron pipe tee on the vent to keep the rain out, but let the smoke pass through.
I have never seen or heard anything about covering the smoke hole either (except for in rain). That is definitely a new one for me unless things have changed. I tend to not spend a lot of time here in the summer while I am out at the lake and just a really busy time at work. But, come Fall and Winter I have more time to dedicate to reading the forum and responding to threads.
That Iron Pipe Tee is a new one for me too, but that if Gosh Darn GENIUS!!! Thanks for sharing that Lipster!