I'm not sure about that, it can be an optical illusion. On some photos they really look almost the same size. On other there's a strong increase towards the bow, which I first thought was on the earlier days. But when I look at all the photos I have downloaded, I would say it's same height for all.
I think I'll make a set with same height , print it on paper and stick it to the hull tonight, then do a few photos from different views.
On the side view, as the plane is, only the starting numbers hull wall is somewhat parallel to the view, then the lower part get's further away. So the letters got tilted a bit wich makes them smaller in hight.
(I hope it's somehow understandable)
Best,Joerg