That's weird. I recall from my first playthrough it being an akira (and being in awe of how awesome it looked to my tiny miranda)
Now, I'm totally going to replay the mission and see what ship roulette serves up for me!
oh, i just remembered another ship that use to stay the same that changes now. the USS Lakota from the under cover of night i think it is. use to be one of the akira variants all the time, now its a chyenee or something when i last saw it.
The NPC model must scale with your level, same thing happens on the mission "Rapier" with the USS Rapier, It is suppose to be a Rapier class, I replayed the mission the mission as a Vice Admiral, it looked like a Fleet Escort when I first found it, when I finished the On-board part of the mission and beamed back to my ship it was the correct model.
once you reach Admiral replay the mission and you'll see what I mean.
It must be a side effect of all the missions scaling with your level, this probably happens with most friendly NPCs that don't have a forced model.
Its like how enemies change depending on your level.
That is my theory anyways.
I made like 15 edits to this post, that is what I get for posting at midnight.