Nebo is sometimes. I think people associate red huskies as being female (like from Balto I guess?). Many people think he's a malamute and he'd be a small malamute and therefore more likely female. I think he has quite a masculine look.

Sydney is almost always mistaken for a boy. The name can go either way and it seems that people believe all black dogs are male for some reason.

I don't recall anyone thinking Reggie was a girl.