It's happened to me too, but mostly in the early days post 3/3 through about summer. In one case, it was the first leg of a connection that posted with a date one day +, but the second flight on the correct day. This was an all domestic, same-day connection.

Have no idea why this happens, but unless its a 12/31 to 1/1 error that forced you not to get the next status level, I wouldn't worry about it.