It's possible I'll address the matter in Wednesday's comic, or do something completely different, but I figure I'd best say it now for the record before assumptions are made: The reason (mostly) didn't have anything to do with the gender of my avatar. That can change based simply on how I feel or want to draw or any number of reasons.
Still, I said "mostly" because I didn't always want to have my avatar be one gender, and I felt sort of awkward about that, and I felt even more awkward about the idea of having a human avatar with that sort of fluidity. So it wasn't THE reason, but it was a factor.
In any case, yeah. There was a really long stretch when I was genuinely uncomfortable including my squirrel avatar. In fact, that discomfort is the real reason my avatar appears in silhouette in this 2011 Q&A comic. It was a sort of compromise with myself.