It's because it's skinny... 80x23 pixels. If your avatar was more square it wouldn't be so obvious. Supposedly avatars are restricted to 80x80 and 100kb, but I know of several that are 120x90.
Mine is 48x55 and big enough!
Ten Forward - 2014 Escape 5.0 TA
Double Yolk - 1988 16' Scamp Deluxe