Right-clicking a sitting cat (for example) while holding a named nametag will do two things; name the cat, and make it stand up. You would expect it to name the cat without making it stand up. It's a minor annoyance, as it makes you have to right-click twice to name a cat once. This could also be very annoying if you want your cat to stay in a very specific spot that's hard to get it back onto if it runs off.