Goodness! That's amazing for a kindergartener! Reminds me of a couple of months ago when DS7 and DD4 were watching the Discovery Channel (or maybe natiional geographic - something like that). There were some Elk on the screen, and DS7 said, "Awww, look at him - he's so cute!". DD4, who has been learning about animals recently (I let them each choose a subject in addition to the basic reading, writing, math - and her subject is animals) said, "He? OBVIOUSLY that's a FEMALE deer. It doesn't have antlers."
DS7 got extremely upset because his four year old sister knew something he didn't.