They have taken the accents into account to center the height, which results in those keys to appear lower than their counterpart (eg. 'ê' is a bit lower than 'e' and all other keys because the '^' was counted as part of the letter).
I remember we had a discussion a while ago (probably around march) about certain keys of the BEPO set which shouldn't be centered this way (I beleive it was the 'ç' key which was faulty in the wiki and had been corrected).
Some of the accent keys seem to be done right:
![Image](http://tof.canardpc.com/preview2/99bf5c5a-24ca-4f54-8f9d-54b35c53ba16.jpg)
Edit: not sure I was very clear so I added another picture:
![Image](http://tof.canardpc.com/preview2/ac26177b-56f4-4230-954a-9f8679f68230.jpg)
Edit2: Muirium summed it up better than me in 1 sentence.