Oh, it's happened.
I don't know if I'd say "often", and I think a more experienced WS-er might have concrete examples; but I've heard/read of the occasional thread to that effect, to be sure.
I've wondered the same because 2 or 3 people who are brand new posters when I first saw posts struck me that way. Of course I then realize that a week ago I was also brand new and posting the first time. Might have struck someone else the same way. MOO.