Just so you know it's not an issue with my custom image there, you can see it happens on the default too (though it's a bit more difficult to see):
Not a big deal, just an FYI.
Also on the page that shows the threads in a forum, the small 48 x 48 image is used, but it is displayed at 36 x 36. Again, not a big deal, but I thought I'd point it out. Someone probably already mentioned it, but I couldn't find the thread.
The only place I can see where the small avatar is displayed at 48 x 48 is in the Profile Posts section. If the thread view is going to display at 36 x 36, the default small avatar image should be 36 x36. Otherwise there is unnecessary image distortion.
Minor points, I realize, but I was just replacing the default icons and noticed these things.