Advancement bug?

I opened a new world in creative and am currently building a house/farm.. I tamed a horse, and for some odd reason, got the "A Complete Catalogue" advancement in the Husbandry section, despite the fact that I haven't tamed a single cat, let alone all ten different variants. This isn't really an issue for me, as I'm not too concerned with getting all of the different advancements, but it's still an odd occurance.
Thanks!
-Gage