Yeah its pretty common for the V-10 to "loosen" up a bit around the 10,000 mile mark. There is/was a lot of discussion about that over on ford-trucks.com when it first came out.
On both of my Superduty's I noticed about a 0.5 - 1.0 mpg increase after the 1st 10k. I'm not watching it closely enough on the Axis as this is my 3rd V-10 and thus I'm just letting it do its thing