HansNZ said:
it is just EXTREMELY common among Americans.
Extremely common to me means something like 4 out of 5 americans say it this way. I can assure you that either you are talking to a group of Americans all from the same region (perhaps a dialect?) that speak this way, or you are using the word "extremely" much too liberally.
You've named Dan Rather - can you name 10 other public figures that speak this way. If it were extremely common, you should be able to come up with 50 well known americans that speak in this manner.
Not to split hairs, it's just that I rarely hear this, and coming from a family with two speech pathologists, I tend to notice these things. Also, I work for an Australian company, and I've heard them make fun of just ebout every quirk in the English language, but this is one I've never heard.
Some differences I've heard:
They think it's funny we say the word 5,500 as "fifty-five hundred." Aussies say "five and a half thousand."
I think it's funny that Aussies and Brits seem to end every sentence with a question mark, or turn ever sentence into a question. ie - my coworker knows I just ordered a steak for lunch - "ordering a steak today are you?"
Other words Aussies and Brits say "wrong"
laboratry instead of laboratory
alumninium instead of aluminum