Originally Posted by
WidgetHead
A lot of times DL will retroactively go back and up-credit from the 25% to the 100% mileage bonus once the status changes in the system, which could take a few days. This happened to me last year, hit Gold on TLV-EWR and flew JFK-LAX-ATL-JFK the day after and only got 25% bonuses, but it got credited back within a week or two I think. Keep an eye on it and definitely speak up if you notice that it hasn't been properly credited after a week or two.
Ditto on this. Thanks to Flyertalk I found this out and received 100% mileage bonus after making gold on my SYD to LAX leg. I submitted a mileage request a few weeks afterwards and it was quickly taken care of.