This has been bothering me for a long time. I say things like “Have you seen this morning’s Washington Post?” all the time. I sometimes catch myself and realize that it’s the same paper all day. The Post doesn’t change in the afternoon. It occurs to me that this might be a holdover from the days when we did have afternoon, evening or late editions. I used to buy two New York Posts every day, for example. I might have picked this up from my parents who used to buy more than one edition of the same paper everyday all the time. Maybe there are other explanations as well, but I think this has to be part of it. “The morning newspaper” is now the only newspaper we have all day (not counting the web stuff) but the phrase hangs around for the same reason we still say “dial” a phone number.