I'd imagine that was because Leeroy used to be on e-fed staff, thus he was allowed a larger avy. Since he has never changed it since he became a regular member again, his avatar is still larger than the limit for regular members. The same probably applies for the person who has the Stone Cold avy, except they were likely a premium member for a year, rather than paying for a lifetime one.
Yours is a WF avatar though - I presume since they are already there they do not fall under the restrictions. It's not like you're uploading a larger than allowed avatar - you're choosing one from a list of images WF provide that are already on the server or whatever.