I noticed this today about the logos between the 4 sites. They all vary in size. Server Fault's logo is 250x48, Super User's logo is 250x60, and the logos for Stack Overflow and Meta are 250x61. I understand attempting to maximize efficiency, and the sheer number of times you serve the logo is pretty huge, but if the dimensions of the CSS are the same between the sites, why not try to make the logos the same dimensions as well?
All that really needs to be done is pad Server Fault's logo 13 pixels at the top, and 1 pixel at the top of Super User's logo. I suspect that the size difference would be almost unnoticeable increasing Super User's logo size, and only somewhat noticeable by increasing Server Fault's.
So, my question is this: Is there any real reason not to make the logos between the sites all a uniform size?