Yoshi's gender confusion

For a long time now, Yoshi has said "good boy!" after doing tricks, or doing things he knows he's supposed to.  He of course caught on to this after me saying it, excitedly, each time.

Likewise, I tell Melly "good girl!" under the same circumstances.  Well, for the past month or so, Yoshi has started saying "good girl!" after he does something deserving of the phrase.  I'm unsure if he's trying to tell me he now identifies as a female, or what.

Actually, I'm fairly sure he feels as if I'm somehow giving Melly more praise by the difference in the phrase, and he wants to ensure he's receiving equal or greater praise than her.

Such funny little critters...